How do I get Players to spawn the size i want?

If you are lost on how to make them spawn the size you want, you may want to change their size inside a PlayerAdded function and then make another function that triggers when the player dies, and change the size of the player inside that.

game.Players.PlayerAdded:Connect(function()
                             -- Change size
end)

if character.Humanoid.Health == nil then
                       -- Change size
end