How to make GUIs that only appear when you play on a specific device only?

Hi guys, its me again. I'm so sorry if I ask too much questions, I'm just a beginner on Lua. I try to make my GUIs on our group game be compatible on other devices, but they just won't fit on the screen. For example, you cannot play on Mobile since the Close button of the Welcome GUI is not visible on Mobile. I want to have other styles of GUIs for other devices that is compatible to it. Is it possible? If so, what could I do to make it? Any answers would be really helpful.