I've been outnumbered by as much as 7 to 1 in War Thunder realistic battles and still won.
Since I've played both games and IL2 I thought I might be able to help some.
-If you get in a 7 to 1 here and you're not B&Zing lower guys or in a 262 there's a very good chance you'll end up dead.
-I suspect the biggest challenge you will have is programming your controllers here.
-I think you will find the game pretty easy compared to WT sim battles as you don't have to manage trim as there is an auto trim setting, there are no engine/prop controls and you don't have to worry about overheating your engine.
-There are icons that come on when an enemy is 6k from you and stays on the whole time he is within that range so there's no ducking behind a hill or tree to hide because the icon doesn't go away.
-The damage model is different in that some planes appear to fly faster when missing a wing and that your engine won't degrade of time when damaged. For the most part it will run at full power until it over temps from damage or the oil pressure goes to 0 and it stops.
-You can't buy planes but there are some planes that you need to save up points to fly.
-The built in comms are used a lot and allow players that are not in squads or on discord to contribute to your SA.
-In my experience about 50% of the players in WT are either new or very lacking in ACM skill. I would not expect that in AH. In my experience you will run into a couple different kinds of players here that make it different.
1: Will only fly in a group and will only attack when they have the numbers and the alt advantage.
2: Single pilots who do the same.
3: Will engage you at any alt, speed or numbers. (these guys are getting fewer and and fewer these days but they are the most dangerous and will most like take your lunch money)
To get up and running quickly I would suggest:
-Download the game and setup your controllers. Once you get that done there is an option to fly offline with drones circling the base that won't attack you. This is a good way to figure out the gunnery model.
-After that there are offline missions you can download and fight AI. This will help you get used to the flight model.
-Once you are able to fly and shoot I would start the 2 week trial and give it a go.
Hope that helps. Good luck!