@rachid I agree, always start out with depressing. Retraction does play a role even with a range of motion that is only vertical. But you're
not putting the scapula in the
position of retraction, you are just keeping tension for retraction to keep your shoulder/body neutral as you pull up. I see guys at my gym new to pull ups or just never really improved and as they pull up, they swing forward because they are not tensioning for retraction to keep control of the movement. Most people already have the retraction strength needed to stay neutral for pull ups and will learn to apply it without thinking about it after some time of training pull ups. If you do chest to bar pull ups, that's going to include a bit more retraction at the top and the scaps will actually be in the position of retraction. But chin to almost bar pull ups, retraction is just to be stable in the pull and is something most will just learn without thinking about it.
Planche requires a lot of protraction strength (and knowing to stay depressed) and front lever requires a lot of retraction strength. In Planche, you actually go into a full protraction position. In front lever, you don't actually go into the position of retraction. You maintain tension for retraction to stay shoulders neutral and not drooped forward.
Google image search Front Lever, look at their shoulders. They are not in the position of retraction. They are tensioning for retraction to keep shoulders neutral though. Same thing with chin to @ bar level or hopefully above.