How to prevent scheduling conflicts?

How do I PREVENT anyone from scheduling me for a meeting during a time
I've blocked off? I don't want tentative scheduling because others will
just leave the conflict and put the burden on me to resolve it. I also
have seen the option to "automatically decline conflicting meeting
requests" but there seems to be no way to activate this without also
activating the "accept" option as well, which I do not want.

My goal is to stop my name from being included on any meetings that
happen when I'm not in the office. My work schedule has me leaving at
3:30 PM but get included in meetings after that all the time.