Leveling up your character / characters in Baldur’s Gate 3 can be confusing for new players. BG 3, like most RPGs, require you to achieve experience points (XP). Once you have acquired enough XP, you can level up.
Gaining XP is quite easy in this game, as it is granted for so many things. Completing a quest, killing your enemies, opening chests, even interacting with other characters!
When you are eligible for a level, you will notice a “cross” or a “plus” sign on the top right of your character portrait.
Click on that sign and it will take you to the level up screen.
From there you can add new skills, abilities, spells as per your eligibility!