Something I remember liking from other games, the main one coming to mind being Fable, is that when levelling and picking abilities it would usually show a small clip displaying the ability in question.
That, however, doesn’t really engage players with actual mechanics, which is the point of onboarding - seeing the skin in action (or trying it out yourself) is more important in action games like Fable or DMC where written description won’t really give you an idea of how skills work.
In BG3, however, showing a video of how skill looks in the game, or even letting player to try it out in a controlled environment won’t help them to understand how the skill actually works, or how it should be applied (what defences it targets, what enemies to target with it, how to make enemy susceptible to the skill etc.)
