Redmi K30 5G package, classed as firmware but only about 851 KB in a 7z archive, which is far too small for a complete phone ROM. It may hold a partial image, loader, configuration file or service documentation, so unpack it with 7-Zip and inspect the contents before deciding how to use it. The name carries no version or region. Make sure it is meant for the 5G model and not the 4G K30, which is different hardware, and keep a backup of the phone's own partitions before flashing anything to it.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @esquematicosdecelulares. Enginerys does not host this file.
How to open a .7z file
High-ratio compressed archive, often used for large BIOS collections.
Back up your own chip before writing any dump, and match the full board number and revision. Flashing guide →