I now have two iPads. I don't want them to both be on the same account. How do I move one to an account for my son?

Help here > Sign in with a different Apple ID on your iPhone, iPad, or iPod touch

Be aware, when you sign in using a different Apple ID, the content from the original Apple ID will be deleted.

I was told you had to go through the family sharing route. Have you tried that?.

Start with this: What to do before selling or giving away your iPhone, iPad, or iPod touch - Apple Support

Afterwards you can activate family sharing if you want: https://www.apple.com/icloud/family-sharing/