It sounds like you're looking at a for Ace Combat 7: Skies Unknown Deluxe Edition . Before diving into a "guide," it's important to clarify a few things—because .XCI is a cartridge dump format used primarily with custom firmware (CFW) or emulators (like Ryujinx/Yuzu), not an official file you'd run on a stock Switch.
ACE COMBAT 7: SKIES UNKNOWN DELUXE EDITION officially launched for the Nintendo Switch July 11, 2024 ACE COMBAT7 SKIES UNKNOWN DELUXE EDITION -XCI-....