I've been trying to make this one for a while any ideas on how to create it. This was solved by DaRealAKASGaming. Paste this script into a local script in startergui!
sm = BrickColor.new ("New Yeller") game.StarterGui:SetCore("ChatMakeSystemMessage", { Text = "Testing message"; Font = Enum.Font.ArialBold; Colour = sm.Color; FontSize = Enum.FontSize.Size96; })