I saw some top runners not collect the 4 color boxes required to unlock the red hand, and instead jump on some cartoon boxes to directly grab the right hand on 1.3, but I haven't found any tutorial to do this skip. Is there any easy consistent setup for beginners like me?

You can just jump from the conveyor belt on the high box with good timing, then just jump on the 2 other boxes to your left, which are a little higher and then you do a precise jump and grab the red hand in the jump by spamming E.I hope this helped

I have no issue climbing on the boxes, but I don't know any visual cues to tell toward where I should jump, and when I should turn around to face off the red hand box

There is an easier version where you jump onto the red hand scanner, look up at the red hand box and just press the E button (console runners use this version of the skip)