Is it normal for a dentist to put on a temporary crown before a root canal, and afterwards put on a permanent crown?

Yes: Unless your dentist uses cad-cam technology to make the crown while you wait, it is standard to wear a temporary crown with your permanent was is being made in the dental lab.

Yes: Yes, this is completely normal.

Yes: This is normal. A tooth requiring both a root canal and crown will often have the temporary crown placed, followed by completion of the root canal. The root canal does not significantly change the shape of the tooth to be crowned, so the permanent crown will still fit very well when it is put on.

Temporary crown: I would say the vast majority of root canals I perform , i dont place a temporary crown first. Reason being is the natural anatomy of an unprepared tooth is better situated to retain a clamp for the dental dam, though there are other ways around it too, but that is my preferred method when possible.

Often recommended: If your tooth is damaged but not lost, a temporary crown can be used to protect its shape and strength before the root canal treatment is initiated.