Here's what I just discovered (might not be news to others though).
Do the following to reproduce;
Settings > Accessibility > Colour & motion > Colour correction > Colour correction Shortcut: ON--select the 'volume keys'-option here.
Now, go
Settings > Accessibility > Colour & motion > Colour Inversion > Colour inversion Shortcut: ON --select the 'volume keys'-option here too.
Now, you have at least two of these enabled. Press Both Volume keys, hold for two seconds. An options card appear. Down right in the card, option 'edit shortcuts'.
Have you been here before?