What is Cross-Platform?
According to TechTerms.com Cross-Platform is "Software that can run on multiple types of computer systems."(https://techterms.com/definition/crossplatform) in Terms of ROBLOX Development, it means the ability to play with other platforms such as Mobile, XBOX, and PC. ROBLOX is versatile in its ability to kinder to different platforms and Cross-Platform is the outcome.
How Do I Configure Cross-Platform For My Games?
Unlike you think, your UI does NOT look the same on all platforms, what looks big on your screen looks GIGANTIC on another screen. That is unless you have your UI configured to fit different screens. That is not your only problem. Interface design is also crucial.
Input is different on all platforms. use code to show correct inputs as displayed here
TheNexusAvenger released an easy way to do this on the devforum
if you have any questions about cross-platform find ways to contact us on the contact page here
signing off, AstraAxis