How to load a character appearance for an NPC in-game?

I've tried to do this many times, I've looked it up on the wiki, and I actually tried some methods myself. I've found absolutely nothing.

Here's what I made earlier, didn't work at all.

spawn(function()
    while wait(15) do
        local mdl = workspace.CharModel
        local char = game.Players:GetCharacterAppearanceAsync(117099978)

        mdl:Destroy()
        char.Parent = workspace
        char.Name = "CharModel"
    end
end)