Q.monkey puzzle trees in pots
I have two very small monkey puzzle trees in pots outside. Can I have some advice? I need to know what size pot and what soil to use, plus should I feed them?

How tall is your monkey puzzle tree and what size pot is it in now? a tree that is a few feet tall would probably do well in a 7 to 15 gallon pot - the bigger the pot the more years of growth it will have in that pot.
The following article will specify the kind of soil and fertilizer regimen that you should follow:
https://www.gardeningknowhow.com/houseplants/monkey-puzzle/monkey-puzzle-indoors.htm