Controls for games on phones

I have no need for a cell phone so I still use a land line, but I’m curious how they deal with game controls on a phone, especially for an mmo like Diablo Immortal. I know that touch screens allow for tactual control, but does that work for everything? Do you plug in a controller or a keyboard or do they have some other way of controlling games? For example, I’m thinking you’d need at least 6 controls to play Diablo Immortal - 1 for each ability.

Bluetooth is a wonderful thing …

Alrighty then. Answered. Thank you.