Hey there π
2 plants in a 60x60 should be fine. You could even do another plant or two depending on your pot size.
Iβm currently doing 4 3-gallons in my 32x32 (autos). Itβs a little tight, so next time Iβd just do 3 so I have some space to move the plants around inside- but you should have no issues
Happy Growing π±