I will not assume that Barcelona will easily get 3 points, yes they are a big club that on paper has everything compared to Betis but football is always unpredictable as expected. In some previous matches Barcelona ended up disappointing. Real Betis just need to find a way to make Yamal not play effectively, Yamal is a key player for Barcelona to always win matches this season.
The Real Betis vs Barcelona match has been going on for 20 minutes and so far there have been no goals scored by both teams. And although what you said is true, Real Betis also have to be wary of Lewandowski and Raphinha because both players are still very good at this time. For now the attacks from both teams still look mediocre, but we need to see how both teams go through the second half later.