I am wondering what the best encryption for Linux at the file level
Many Linuxen have LUKS or a FUSE (user file system) utility that does this. VeraCrypt is what I would use, because it’s portable (including on things like USB keys or to cloud storage.)
A random Google landed on this: 5 Best Free and Open Source Encrypted FUSE-Based File Systems - LinuxLinks
Also, welcome to the community
Can also recommend VeraCrypt, I’ve used it personally and professionally with success.
Thanks for the suggestion