How to make a script when you run in a part you gain speed?

my script is: i added it to a part which i thought it would only work while you are in a part but it didnt work

game.Players.PlayerAdded:Connect(function(plr) local loaded = plr:HasAppearanceLoaded() while not loaded do wait() loaded = plr:HasAppearanceLoaded() end

local StartingSpeed = 5
local Speed = StartingSpeed
local SpeedMultiplier = 1.002
local Delay = 3
local human = plr.Character:FindFirstChild("Humanoid")
local debounce = false
human.Running:Connect(function(plr)
	while human:GetState() == Enum.HumanoidStateType.Running do
		wait()
		if human.MoveDirection.magnitude > 0 then
			if debounce == false then
				debounce = true
				Speed = Speed * SpeedMultiplier
				human.WalkSpeed = Speed
				wait(Delay)
				debounce = false
			end
		end
	end		
end)	
plr.CharacterAdded:Connect(function(char)
	local humanoid = char:FindFirstChild("Humanoid")
	humanoid.WalkSpeed = Speed
	humanoid.Running:Connect(function(plr)
		while humanoid:GetState() == Enum.HumanoidStateType.Running do
			wait()
			if humanoid.MoveDirection.magnitude > 0 then
				if debounce == false then
					debounce = true
					Speed = Speed * SpeedMultiplier
					humanoid.WalkSpeed = Speed
					wait(Delay)
					debounce = false
				end
			end
		end		
	end)	
end)

end)

Do you mean like you're faster inside a part and return to normal speed when leaving it?

If yes, then this will be the script. I recommend using my module that detects when a part or a model is inside a specific part. You can require it using require(10601121934) or getting it from the website.

-- Normal Script in ServerScriptService
local Players = game:GetService("Players")
local RegionPartService = require(10601121934)

local SpeedZone = workspace.SpeedZone -- for this example we have a part called "SpeedZone"

Players.PlayerAdded:Connect(function(Player)
	Player.CharacterAdded:Connect(function(Character)
		local Humanoid = Character:WaitForChild("Humanoid")
		
		while true do
			local isCharacterInRegion = RegionPartService:IsPartInRegion(SpeedZone, Character)
			
			if isCharacterInRegion == true then
				Humanoid.WalkSpeed = 16*2 -- doubles the player speed
			else
				Humanoid.WalkSpeed = 16 -- returns to normal speed
			end
			task.wait()
		end
	end)
end)

but if you want to make your speed faster after touching the part once, you can simple use the BasePart.Touched event.

-- Normal Script inside "SpeedZone"

local Players = game:GetService("Players")
local SpeedZone = script.Parent

SpeedZone.Touched:Connect(function(otherPart)
	local otherCharacter = otherPart.Parent
	local otherHumanoid = otherCharacter:FindFirstChildWhichIsA("Humanoid")
	local otherPlayer = Players:GetPlayerFromCharacter(otherCharacter)
	
	if otherCharacter and otherHumanoid and otherPlayer then
		otherHumanoid.WalkSpeed = 16*2 -- doubles the player speed
	end
end)