This is not possible on iOS due to restrictions made by Apple.
Yeah, and it’s really unfortunate. Another flight game, it’s not really a sim, it’s a game, called SimplePlanes has a “mod” feature, but unfortunately because of an update Apple did a few years ago, mods can no longer be downloaded on iOS. Add Ons for Aerofly fs2020 CAN be downloaded, but only on android. They will Not work on iPhone
I’m not totally sure, and I don’t recommend this, but I’m pretty sure that there’s an application on PC where if you connect your iPhone, you can modify all files, like game files, and put add ons in there. I don’t recommend this because I’ve never tried this, and because Apple doesn’t really allow this, something could happen to your iPhone, not totally sure.