Transferring ipads

My sons iPad is very old and my husband agreed to let him have his iPad that he doesn’t use anymore. I would like to take all of my sons stuff on his iPad and transfer it to my husbands. Including the Apple ID and password. My son has his own Apple ID and pass. All the info I’ve found tells how to transfer old iPad to new. This isn’t a new iPad necessarily. We just want yo transfer to a new name. Help please!