>>319054307
this. 

for ultra immersive full body It's wildly important to make a rig to your body and scale everything to those proportions. you don't have to be your own exact height or anything but you just need to be to scale. 
Since it's wednesday, here's my tip before I run off to do tangentially related work stuff: 

First - 
Measure your arms fingertip to fingertip. 
That's your height. Armspan in VRChat determines your view scale and literally everything else follows it. Yes, really. 

The four MOST important measurements in the entire game are the position of the hip bone relative to your hip trackers, and their distance from where you place the view ball, and your two hands, so basically the HMD front to your hands, and then to your hips. Feet are much less important, unless you're below your real feet. 

AV3 and just vrchat in general has changed the rig weight influence in the last 5 months to work MUCH, MUCH better if you have a properly weighted upper chest bone, too. So do that if you can. 

But above all, measure your fingertip to your elbow in cm, and your elbow to your neck in cm, and scale the arm bones to match that on the x axis EXACTLY. 
It helps if you set the parent influence of the hand bone to none (not none legacy) before you do that. Mirror on x in the top right. 

Get that right, and make sure the hip bone is smol and EXACTLY the right distance (to scale) from where your viewball would be on your real body from your hips, and directly parallel to your hip tracker. 
Do that and everything falls in line. 

Bonus points scale your legs too. Many models at vket 5 are learning this, especially the ones made by people in the dance community figured out that long legs are garbage. 

Galaxy brain mode: create twist bones and use constraints so elbows and knees bend correctly.
rootmotion VRIK "DRAGS" on the unity mechinim skeleton. Consider that when you rig.