You don't need to extract every file individually. Tools like 7-Zip or WinRAR are smart enough to see the sequence. Right-click on Part 1 and select "Extract Here".
: To open and extract the contents of a .rar file, you can use software like WinRAR (for Windows) or other archive utility programs that support RAR files. POKLEGARC-NSwTcH--BASE--XCI-Ziperto.part2.rar
This is the file format. An XCI file is a digital "dump" of a physical game cartridge. It differs from an NSP file, which is the format used for digital eShop titles. You don't need to extract every file individually