Id say it goes both ways. Ive always been relaxed, introverted, low aggression, give no fucks, you know typically "stoner traits".
What i noticed tho is on weed my personality is very polarizing in that direction. i get even more relaxed, give even less of a fuck and honestly cant get mad at all. Like recently i took a longer tolerance break and i noticed how much aggression i have been repressing.
im 20 never hit anyone in my life and recently on a longer tolerance break i lost it and beat someone up pretty bad (was drunk too tho). And also i noticed how i actually do give some fucks but when i smoke weed daily i forget about that etc..
TLDR If you smoke weed every day and never are really sober weed will change your personality, but if you do smoke daily your personality probably was that way initially just less extreme