6x6 is for a beginner and it's not too much imo. They need to learn to squat properly, get volume in and to prepare the body and joints to lift heavier later on.
OP I outlined what to do:
Learn to Sn or CJ (bar work, hang positions and progress on to lifting from the floor, the better you get the less time you spend from the hang and the more time you spend lifting from the floor)
FS or BS
Technical work (Snatch balance, rack Jerks, lifts from the hang, ohs to help your mobility if you need it, any exercise that helps your olifts)
Strength exercise (whatever exercise you want, pull ups, military, oly deadlifts, oly pulls, pulls to mid thigh, curls, dips, bench press, literally whatever exercise you want to do)
Do that 3x a week. Just alternate Sn and CJ days and repeat. I hit 116/143 @ 83.5kg off the back of that. There is no need to get fancy yet when your full lifts aren't proficient.
Box squats? Forget about them.
The problem with new people without a coach is they take bits and pieces of a programme from different sources and it just doesn't work. IT has too much of everything. So the net result is nothing.