How can i make it so the players in my game are only Block Rigs?

so i'm making a survival game, and i need my player's characters to only be block rigs in order for my character customization to work as planned. Here is what I tried:

local players = game:GetService("Players")
local player = players.LocalPlayer
local character = player.Character

for i, object in pairs(character:GetDescendants()) do
	if object:isA("CharacterMesh") then
		object:Destroy()
	end
end

I'm using r6 rigs to make this, so the characters should have the Character Meshes inside them. this was a script in serverScriptService. I got no errors but it didnt do as planned. If anyone could help, it would mean alot. Thanks!

#This isn't something you would do in a script

you want to use your place's Avatar Settings. In Roblox Studio, go to Home > Game Settings > Avatar. Its fairly obvious how to enable R6 and customize the character from there.