Sicilian closed variation, light square bishop

when you do the white side of a closed sicilian, what are you supposed to do with the light square bishop? Are you supposed to lock it out of the pawn chain so it has space, or keep it on inside the pawn chain so it plays on the kingside? i have seen people fianchetto it, but that seems to go against the closed nature, of the closed sicilian.

but anyway, can you tell about the advantages to the fianchetto bishop. and what whites plan would thanks.

thank you that makes alot sense.

The bishop on f8 problem is why black fianchettos kingside in the mainline of this opening also.

The light-squared bishop is considered a problem piece every time you play the sicilian, not just when you play a closed one. That's why Bb5 and exchanging it off immediately while slightly helping black develop is considered quite valid. Bc4 and Be2 are both quite valid, but the idea of Bc4 isn't really as a great attacking piece but rather putting it on a constructive square. Be2 is probably considered better unless you're castling queenside.