If you are running out of space on your internal drive, then you need to replace the internal drive with more storage space, or remove files that you no longer need. If you
need to be able to search through all of those files, then those files will STILL need the space somewhere. If you fill up the internal drive, then you need to transfer some, or most of those files to an external drive. It's possible to have as much storage space as you may ever need. All you need for that is money.
If you will be using only a Windows PC, then it makes good sense to move all your old files to a native format, such as NTFS, so you don't have to use a file system decoder to read the files stored on a non-Windows format, such as AFS, or APFS.