Speed 64

-- LocalScript inside StarterPlayer → StarterPlayerScripts

local player = game.Players.LocalPlayer

player.CharacterAdded:Connect(function(char)
	local humanoid = char:WaitForChild("Humanoid")
	humanoid.WalkSpeed = 64
end)

-- also sets speed if the character already exists
if player.Character then
	player.Character:WaitForChild("Humanoid").WalkSpeed = 64
end