Looking at their H2H in La Liga, Barcelona have won more matches both home and away and with the current positive conditions I doubt a draw will happen I am more confident that Hansi Flick's squad will get 3 points besides that because Real Sociedad are not in good form this season in 12 matches they have only scored 10 goals which shows their attack line is not impressive.
I am questioning the odds given by the bookies maybe they consider because the match was held at Real Sociedad's home ground but the odds are quite profitable and worth betting on.