I have a 200 amp max per bar breaker in my home and I would like to run power for outlets in my garage. I am thinking 60 amp box with 20 amp gfci outlets. I am not sure if I should use 8 or 6 gage wire fom my breaker to the new one, also, hat type of box should I use in the garage? Also, I am wondering how to wire up the gfci outlets? Thanks!

Assuming NM-B cable (Romex) you cans use #6-3 plug ground and use a 50 amp breaker to feed the new panel.

What type of construction will dictate what type of box is used for the new outlets.

How to wire GFI outlets? Same as a standard outlet.

The new panel will need a separate equipment ground bar accessory to keep grounds and neutrals separated in the new panel, and do not install neutral bonding jumper.

If the garage is a separate building , at least one ground rod will need to be installed and connect to the equipment ground bar using # 6 copper wire.