babies and teens are all capable to consent, the only thing that needs to change according to age is the action

[HumanBeing]

I think is quite obvious but everyone who has the ability to communicate (verbally or not verbally) with humans can consent.

the main (if not only) age-related issue people should be cautious about is what actions an X year old person body can handle or not, for example you can't penetrate a baby or toddler because their bodies aren't ready for such action and therefore will suffer severe harm if you do it regardless of consent.