I ran across these scripts for GIMP: https://jfotography.net/actions#gimp

However, even though they say script, when downloading them and opening them up in Notepad, they are color settings. Are they color settings, curves, or scripts? How are they installed in gimp?

These are curves.. drop them into your curves directory, i found the curves directory in
~.config/GIMP/2.10/curves/

your version numbering might be different.. but you will figure it out.

Thank you, AdmFubar. I'm saving the presets in Curves and keeping the orginal files in Gimp's filters folder.