Is it possible after (1) organizing a meeting, or (2) accepting an
invitation, to change the "show as..." to tentative or free without anyone
else seeing the change?

What I'd mean is that I want the organizer to only see that "yes, I'll be
there", but for my own scheduling, I'd like to show on my calendar that I'm
free/tentative. Similarly, if I schedule a low-priority meeting, I'd like to
change it to tentative, but not have the "show as" change for the people I've
invited.

Does that make sense?

I know I can modify the "show as" option, but I don't know how it looks to
other people on the meeting.

Thanks!