I know Raphinha plays as a left winger for Barca, but just to be certain, he's played different roles in other clubs he's been in. I did a quick search, and I found out that he can also play as a right winger and an attacking midfielder. That's good, as it will give Barça options in case any of the attacking players get injured, he can easily make a switch. Also, I think he'll make a good striker, though I'm not sure he's played in that role.
This is exactly why I'm not worried about Raphinha if Barcelona signs Nico Williams. Raphinha is a very versatile player. He played as a right winger in Leeds and his first season in Barcelona. Under Xavi, he played his best football when he was moved to the AM role, where he was playing behind the striker. Last season, he played the LW and produced 56 G/A. He is a very hard worker, and wherever he is told to play, he plays it very well with all his mind. I don't think the arrival of Nico will cause him too much trouble.
I've ever seen him play as a striker, but I don't think he can excel there because he likes to run into spaces. As a striker, he will be crowded by defenders. I think he might excel as a false 9 because he moves around and presses a lot, but I'm not very sure.