For Fire Emblem Engage (specifically related to NSP/XCI files for emulators or modified consoles), the updates and DLC content are typically distributed as separate NSP files that must be installed on top of the base game (XCI or NSP).
XCI (NX Card Image): This is an exact duplicate of the physical game cartridge. fire emblem engage switch nsp xci dlc update
: This is a raw cartridge image, often used as the base game file. For Fire Emblem Engage (specifically related to NSP/XCI