Help with Dos games

I got a mm+ a couple months back and I love it so much. Im 23 tho and didnt grow up with dos but I love old computer games like that from what I have played. I really wanna get into dos on my mm+ but idk where to look. Like obviously ik how to find a game and add it to the device. But idk anything abt dos, abt the games, or if I need to tinker with setting on onion or retroarch or anything for them.

Can some one please point me in the right direction