How would it be possible to implement a turn-based system in a game that includes movement, item use, and attacking?

I'm making a strategy game where you can move, use healing items, melee attacks, ranged attacks, and other methods in the future. So far, I've managed to program the movement system, which is to double-click only once, only around the area (in this case, the field is composed of hexagonal tiles, and they are glued together, so the player has the chance to move to the 8 spaces next to them).

I'd like to implement a shift system where you press a button on the screen to pass the shift. I would appreciate any help you could provide.