We have a 200 amp main panel. We added another floor and decided to add a new sub panel of 100 amps. Is this OK? Should the wire gage be different from 100 maps? Your help is appreciated.

Typically, #2 aluminum 4 wire SER cable is used for a residential 100 amp feeder.

Typically, #2 aluminum 4 wire SER cable is used for a residential 100 amp feeder.
Thank very much.