The new difficulty options menu from Ver. 1.11.36 covers many bases already. Still, certain tweakworthy aspects of the gameplay remain untouched - the chance for getting loot ("Legendary", "Epic", "Worn by enemy" and "Death Item") is one of these. 

All loot that is rolled in Starfield's vanilla loot tables has a chance of a "none" roll, effectively skipping this loot draw attempt. DOE Loot adjusts these vanilla  "none" chances, allowing for more loot on the easier or less loot on the more difficult settings of DOE Loot. With Legendary and Epic items this is about skipping a possible second or third trait.

05/20/2024: v1.1 released; removed the category "Other loot / General" as this let to unwanted extra occurences of weapons in NPC inventories; added the new "Death Item" category instead (see details below)

To have more fine control DOE Loot has four subcategories (choose one setting/file from each of these four categories):

Legendary loot refers to all golden, i.e. legendary items, with three special traits. In vanilla there's only a 10% chance that a special item gets its third trait and therewith fully develops into Legendary status, ie a 90% chance of "none" roll. DOE Loot Legendary affects this as follows:
Very easy 30% (ie 70% "none" chance) | -0.75% suggested XP Modfier
Easy 20% (ie 80% "none" chance) | -0.5% suggested XP Modfier
[Vanilla     10% (ie 90% "none" chance]
Hard 7,5% (ie 92,5% "none" chance) | +0.25% suggested XP Modfier
Very hard 5%    (ie 95% "none" chance) | +0.5% suggested XP Modfier
Extreme   2,5% (ie 97,5% "none" chance) | +1% suggested XP Modfier

Note: This means for example that on "easy" (80% none roll, ie 20% success chance) you have twice the chance that a two trait "epic" item is a legendary three trait item instead (vanllia had 90% none, ie 10% success chance).

Epic loot refers to all purple, i.e. epic items, with two special traits. In vanilla there's only a 25% chance that special item gets its second trait and therewith partially develops into Epic status, ie a 75% chance of "none" roll. DOE Loot Epic affects this as follows:
Very easy 75% (ie 25% "none" chance) | -0.75% suggested XP Modfier
Easy 50% (ie 50% "none" chance) | -0.5% suggested XP Modfier
[Vanilla     25% (ie 75% "none" chance)]
Hard 18,75% (ie 81,25% "none" chance) | +0.25% suggested XP Modfier
Very hard 12,5% (ie 87,5% "none" chance) | +0.5% suggested XP Modfier
Extreme   6,25% (ie 93,75% "none" chance) | +1% suggested XP Modfier

Death Item (new in v1.1., replacing "Other loot / General") alters the chance that humanoid/robot enemies of various factions drop an extra death item from their loot tables. In vanilla this is a 100% chance. The three setings of DOE Loot Death modify this as follows:
[Vanilla     100%]
Hard 50% | +0.5% suggested XP Modfier
Very hard 25% | +1% suggested XP Modfier
Extreme   10% | +1.5% suggested XP Modfier

Worn by enemy refers to the chance that an enemy drops an item he has actually equipped like e.g. his helmet. As these items are based on the level of NPC/enemy and not the player level, these are potentially very valuable drops (think farming high level enemies). The vanilla base chance for this to happen is 10%. DOE Loot Worn sets this chance to the following values:
Very easy 100% | -2% suggested XP Modfier
Easy 30% | -1% suggested XP Modfier
[Vanilla     10%]
Hard 5%  | +0.5% suggested XP Modfier
Very hard 2,5% | +1% suggested XP Modfier
Extreme   0% | +1.5% suggested XP Modfier

Note: Enemies are hardcoded to always drop their weapon. This cannot be affected by DOE Loot. There's also a limit of max. items an enemy can drop, so even with 100% there are occasions where you will not find all worn equipment (cause other loot was also generated in inventory of the NPC/enemy, capping out he max number of loot drops).

05/21/2024: XP Modifiers can now be realized via XP Unchained

How it was done
DOE Loot is mainly realized via the Console Command Runner Updated mod, which runs the respective included .toml file for one of the five settings of DOE Loot from each of its three folders wtih .toml files (Legendary, Epic and Worn). DOE Loot Death is an .esm mod though, made with sf1edit.

Installation

• Please install Console Command Runner Updated at Starfield Nexus - Mods and Community (nexusmods.com) (which requires SFSE and the SFSE Address Library Plugin)
• Make sure to enable Archive Invalidation
• Then please install Plugins Enabler 
• Download the DOE Loot mod, unzip it and place the  .toml file of your chosing from each of the three categories with .toml files (Legendary, Epic and Worn) into the folder ".../Data/SFSE/plugins/ConsoleCommandRunner"
• Place .esm of your liking from DOE Loot Death (hard, very hard or extreme) into your game's data folder 
• In your plugins.txt file please add the correct line:  *DOE Loot Death Extreme.esm or *DOE Loot Death Very Hard.esm or  *DOE Loot Death Hard.esm (preferably at the end, so the changes are not accidentally overwritten by other mods)
  

Credits
Hugs to Bobbyclue and Meridiano for  Console Command Runner Updated at Starfield Nexus - Mods and Community (nexusmods.com)
Finally, without xEdit and Elminster's work of a genius all this would not be possible, so, many kudos to Elminster and team.

The whole DOE Series and friends
DOE Resources
DOE Resources at Starfield Nexus - Mods and Community (nexusmods.com)
DOE Sell Price
DOE Sell Price at Starfield Nexus - Mods and Community (nexusmods.com)
DOE Starpower
DOE Starpower at Starfield Nexus - Mods and Community (nexusmods.com)
DOE Loot
DOE Loot at Starfield Nexus - Mods and Community (nexusmods.com)
DOE Ammo Rarity
DOE Ammo Rarity at Starfield Nexus - Mods and Community (nexusmods.com)
DOE Ammo Prices
DOE Ammo Prices at Starfield Nexus - Mods and Community (nexusmods.com)
DOE Skill Progression
DOE Skill Progression at Starfield Nexus - Mods and Community (nexusmods.com)
DOE Research
DOE Research at Starfield Nexus - Mods and Community (nexusmods.com)
DOE Less Shortcuts
DOE Less Shortcuts at Starfield Nexus - Mods and Community (nexusmods.com)
Replicant
Replicant at Starfield Nexus - Mods and Community (nexusmods.com)
XP Unchained
XP Unchained at Starfield Nexus - Mods and Community (nexusmods.com)
Sneak Damage Hotfix
Sneak Damage Hotfix at Starfield Nexus - Mods and Community (nexusmods.com)
Equipment Level Requirements (ELR)
Equipment Level Requirements (ELR) at Starfield Nexus - Mods and Community (nexusmods.com)
NGXP Plus / NGXP Plus Risk
NGXP Plus at Starfield Nexus - Mods and Community (nexusmods.com)
Minimum Enemy Level
Minimum Enemy Level at Starfield Nexus - Mods and Community (nexusmods.com)
Fauna Protection Initiative
Fauna Protection Initiative at Starfield Nexus - Mods and Community (nexusmods.com)
Spongecop
Spongecop at Starfield Nexus - Mods and Community (nexusmods.com)
Building Rarity
Building Rarity at Starfield Nexus - Mods and Community (nexusmods.com)
Minimum System Level
Minimum System Level at Starfield Nexus - Mods and Community (nexusmods.com)