I really hope someone can find this animated movie I don’t remember it but it’s pretty relative and not that old.
It starts off futuristic. This kid gets moved to a new town with a male figure that I’m pretty sure isn’t his dad but is some sort of future tech/scientist. The kid likes this girl and is in the guys lab when he finds this beaker filled with liquid that will make him cool and confident so he decides to drink it. He becomes like a totally different person and the girl starts to like the confident him but no one knows it’s the same person. Anyways when he isn’t in his egotistical form he gives the girl a bike chain for a necklace as a gift. Eventually something happens to the drink and he can do longer be the cool self he always wanted to be and that’s about all I remember.
One line I remember went something like “I get it, new town, new friends, new girl” when he finds the drink his male guardian figure makes him and this is playing from a screen as like a video message.