The search term "FIFA 18 Switch NSP" often leads to piracy links. However, there is a legal way to generate this file if you own the game. Nintendo allows users to dump their digital purchases for backup purposes (depending on local laws).
To fit the game onto a manageable NSP file size (approximately 9.5 GB to 12 GB after updates) and run on the Switch’s mobile Tegra X1 chip, several features were cut: fifa 18 switch nsp
Please note that downloading and installing NSP files may void your warranty and may be against the terms of service of Nintendo. Be sure to only download NSP files from reputable sources and use them at your own risk. The search term "FIFA 18 Switch NSP" often