how to make it so that if the player joined the game his speed and jump is 100?

You got to tell the script which player’s character is it! To do this, you can try the script below:

game.Players.PlayerAdded:Connect(player)
player.character.Humanoid.WalkSpeed = 100
player.character.Humanoid.JumpPower = 100
end

In the script, player is a parameter of the event PlayerAdded. It will tell the server ‘who’ joined the game. Then, after knowing who joined, the script will find the player’s character and change his walkpower and jumppower to 100

Hope I make it clear :D

put a script inside ServerScriptService then the code should look like this:

game.Players.PlayerAdded:Connect(function(player) -- gets the player when they join
    player.CharacterAdded:Connect(function(character) -- wait till the character loaded

        local humanoid = character:WaitForChild("Humanoid") -- define humaoid
        humaoid.WalkSpeed = 200 --  change it, walkspeed :)
        humanoid.JumpPower = 200 -- change it, jumppower
    end)
end)

hope i helped LOLLOLOLO

Depending on whether or not you want to achieve this through a script, this can vary. For a less complex version, you would just go into starterCharacterScritpts, and change the walk speed/jump power. Although, I recommend doing this through script, because you can later change or adjust the speed, and or jump power. Put this script into the server script service, as a script:

game.Players.PlayersAdded:Connect(function(player)
    player.CharacterAdded:Connect(function(character)
    local hum = char:WaitForChild("Humanoid") 
    local w = hum.WalkSpeed 
    local j = hum.JumpPower
    w = nil -- put your walkspeed here (default is 16)
    j = nil -- put your jump power here 
    end)
end)

This should work just fine, and if you want to tie this to a remote event, or a touched function, your free to ask

Select StarterPlayer in the explorer.

Change CharacterWalkSpeed to 100, and CharacterJumpPower to 100.

You can easily do this in Game Settings. Just change the player speed and jump to 100.