Is this crossbar setup fake?

[ShinigamiB06]

no I have something similar myself actually. Though I just have 1 bar at the bottom. You can hide slots on the bars when they aren't in use. When you do the only ones you see are the ones with icons in them so he could have multiple horizontal bars with that settings to hide the ones without icons. You can also turn on vertical hot bars so he could also just have 2 vertical ones up there. But yeah it can be done.

and how do you do that??

[MysticNeko]

and how do you do that??

Character config and hotbar settings. I'll assume its a computer only thing but yeah everything you can do should be right there. The way I have it set is I have the crossbar and under it I have the first hotbar (which for the most part is pretty much full) I have the keyboard set up to NOT start chatting when i start typing and I've learned to quickly move my hand to tap a number when I need it (which is for skills I don't use as often as skills on my crossbar itself)