- Edited
Godot is very event-driven. If you're tempted to use yield, you're probably thinking too linearly, and yield won't do what you want anyway. You'll probably have better results if you use signals to call the functions (for example, from a timer).
Remember that yield only returns execution to the calling function, so whatever is next in the function your for loop is in will be executed, including the next _process() call, if that's where the loop is at -- so you could end up yielding repeatedly. You'd have to post more code for me to be certain of whether it could work or not. I'm not even sure what you're trying to accomplish.
If you still think yield is the right solution, you have to pass it an object that will send a signal at the time to resume your loop. If you're planning to give it an object that signals immediately, you might as well just use the original loop.
If your functions are launching animations or other asynchronous processes, you might have the animation signal a controlling object that launches the next process in a queue. I can't be more specific without knowing what you're doing.
TLDR: Don't use yield.