Emulator

The apply step? Please elaborate, I'm probably being dumb and don't realize it but I don't remember of there ever being any sort of "Apply" button for cheats.

See attachment of the cheat manager. The Apply button is at the bottom-right.

Turning on/off the cheat by checking it should be enough, no need to press an additional button to activate/deactivate the effects.

"You can disable them while running in the cheat manager, I believe."

Yes, but the request is to activate the cheats by just turning them on/off by checking the left box, without having to hit Apply.

What if you want to turn off multiple codes on the same frame, you know? Then it becomes having to pause the emulator, disable/enable cheats, etc. I don't know. Someone else who uses more cheats than I do will need to comment.

"On the same frame"? Then for that you would have to pause the emulator anyways, no?
And if you pause, you still don't have any need for the "Apply" button.

Every other popular emulator out there allows you to enable cheats by just checking them, and so far no one has complained about that method. Dolphin is the only emulator I've tried that makes you first turn on a cheat, and then hit Apply to make it work.

It's not a dealbreaker, but it makes it particularly bothersome having to take those 2 steps when you are creating and testing cheats on the emulator.

It would be more streamlined if you just turn the cheat on and see its effects immediately.