It's hard to find a player at Lionel Messi's level who has good ball skills and free kicks. Barcelona don't have that now and of course they always struggle to find a way out when expecting a free kick goal in a match. Honestly, I don't know who is worthy of being relied on to do that apart from Raphinha, Lewandowski or Ilkay Gundogan, but Barcelona is still having difficulty finding that in their squad.
I think Lamine Yamal might be able to transform into a versatile player for Barcelona if he trains hard. Lamine has good skills and he also has good passing accuracy, so if Xavi is really able to improve his skills then Yamal will be very useful for Barcelona in the coming seasons.
I am more inclined to see good players who are able to carry out free kicks by Gundogan or Raphinha. Obviously there is no ideal replacement figure who can match Lionel Messi in taking free kicks at the moment, but over time this figure will be in the Barcelona squad because now they have talented young players who continue to struggle to make place in the main squad . Xavi still trusts Lewandowski as the person who takes free kicks, but his ability has not yet reached his level of satisfaction.
Lamine Yamal is just playing for his professional career in the Barcelona senior team and I don't think he is ready to take on this task, especially since the mentality of playing in the Champions League is very different. But as a preparatory step, I agree that if Xavi will give him the opportunity and it also depends on how Lamine Yamal can train to continue developing his talent and potential.
At least in the group stage you can trust and let the newcomer prove himself, because Barcelona are not in the most difficult group, you can even experiment a little. Although there is also La Liga for that, so as not to take risks in such a tournament, especially for Barcelona this season it is very important. So far I see that Barcelona can definitely get out of the group, maybe even reach the quarter-finals, and then it all depends on the opponent