How do you change a player's walkspeed through a script?

[NurZwanzigBuchstaben]

I edited my reply with a function you can use to change a Player’s WalkSpeed. Just call it like this:

ChangeWalkSpeed(game.Players.Pancake1824, 50)

That checks if the Player has a Character and a Humanoid, if they do, change their WalkSpeed to the one you desire.

@SimplyData

This is just an example code you can fit to your script (as posted above)

local function ChangeWalkSpeed(Player, NewWalkSpeed)
 if Player and Player.Character then
  if Player.Character:FindFirstChildWhichIsA("Humanoid") then
   Player.Character:FindFirstChildWhichIsA("Humanoid").WalkSpeed = NewWalkSpeed
  end
 end
end