Right, Fold 2 should have plenty of power. I assume you’re on a stock ROM, so you can’t apply performance governor, or do some other kernel tweaks. On my phone, being on stock Android 10 instead of rooted Oreo, I’m seeing a heavy performance hit due to Samsung’s own crappy cpu management.
This can be alleviated though by using Samsung Game Launcher, along with Game Booster Plus (https://galaxystore.samsung.com/detail/com.samsung.android.game.gameboosterplus). Add Magic Dosbox as game to the Launcher, then configure GBP to run it in max fps mode.