Hello @bambi and welcome to the forum!
There is the plugin Theme Creator Extension which allows you modifying color schemes and which maybe was used to create these color schemes too.
In case that it is not known to you, you install plugins in Krita by clicking on “Tools” >> “Scripts” >> “Import Plugin from File” and in the dialog that opens, select the file you just downloaded, confirm the selection, then confirm Krita’s message that the plugin is installed and restart Krita. Then you have to search in Krita under ‘‘Settings’’ >> ‘‘Configure Krita’’ >> ‘‘Python Plugin Manager’’ for the plugin you just installed and activate it by checking the box in front of it. Then confirm with “OK” and restart Krita to be able to use the plugin.
For even deeper modification there is another, or should I say an additional, plugin to modify Krita’s look, it is called Style Sheet Loader Extension.
Michelist