Cosmetics

Hi

I'm new to POE2 and never played the previous title.

I would like to know if the starter pack cosmetics share among different characters or not?

If you buy a cosmetic you have that as a singular item that can be shared, like a piece of gear, between characters.
Example: You buy a cape, you equip it on a character. Then you make a new character and want to equip the cape on that one instead. The game will tell you that you have that cosmetic already equipped on another character and ask you if you want to remove it from that one and give it to the other. If you accept, the cape will change characters but it won't be on both at the same time.