Is there any way to change my avatar to a custom one on VRChat?

I'm currently unable to launch the VRChat program, so for now I'm limited to the VRChat website. It shows a tab for "Avatars," but the only thing I can do is reset to the default robot or pick one from a set list. I have a custom file for a specific model I want to use, but there's no buttons anywhere to upload files. There is also no search bar, so I can't tell if the custom avatar I want is already out there.

I'm prepared to accept an answer that says, "No, sorry, you can only customize your avatar within the game."

I've searched and tried if we can change avatar from outside of VRChat client, but sadly, it seems to be impossible to change avatar without launching VRChat, as of now (of course, aside from changing avatar from VRChat website to default/some set of avatar.)

So... No, sorry, you can only customize your avatar within the game.