I cannot in good faith recommend this game to anyone because of its egregious abuse of pay-to-win mechanics. And I'm not even talking about the premium ammo or premium tanks stuff. I'm talking that you will have a worse experience as a free-to-play player in any given tank than someone who regularly pays money and uses the same tank.
For any given match, and for any given tank, if you play the game without spending a dime, you will statistically have higher dispersion, higher aim bias, lower camo, and lower view range than someone using the same tank but who regularly spends money on the game.
It took me a good long while to figure that out, until I ran an experiment recently with the Rolling Thunder event. I actually have two accounts, this one being my main account and free-to-play account. I managed to get the Grom tank completely free. My other account, I made that very recently and purchased the Grom without playing.
Then I ran dozens of test battles in the Grom across both accounts. What I found was that using the account that I purchased it in, my accuracy was significantly better, dispersion significantly lower, and average damage per battle was much higher. Meanwhile in the free-to-play account, playing in the exact same way and as the exact same person who's doing the playing, it was an entirely different story. It was shocking just how much worse the experience was. I've shot at a T-50-2 using this tank and had it bounce the shot.
The conclusion is this: you will not have fun for long if you try to stay free-to-play. The game actively punishes you with lower performance stats on your vehicle if you do. That's why those numbers exist, is so the game can adjust them based on the user playing that vehicle. It's disgusting how much of a better experience you get when you spend money on the game.
I'm sure War Thunder does this too, so the answer is to not play a free-to-play game. Find a game that you have to pay for up front in order to enjoy, instead of having to shell out $100 USD for the newest premium tank in order to have fun in any tank.

cant use my existing wargaming account

This game makes me want to kill myself