I go with a set schedule of Monday, Wednesday and Thursday in office. If a holiday falls on those days, my argument is that is an office day. I keep to that schedule no matter what. If HR wants to complain, my counter is that I'm consistent with my office time.
FWIW, I'd recommend a set 3 day schedule as it demonstrates you follow the company's request. I'd also suggest that Monday be an office day as most holidays fall on Mondays.
Always Monday
MLK
Presidents' Day
Memorial Day
Labor Day
Columbus Day
Thanksgiving is always a Thursday
Christmas, New Years and July 4th ... many folks take off around those dates anyway.
That leaves Juneteenth and Good Friday (if you're in wealth). At that point, I don't care enough to complain if they fall on my scheduled WFH.
Your best defense against HR is to be consistent. If you demonstrate that Monday is an office day, then they can't complain about holidays that fall on a Monday counting as an office day. I doubt the company would get so petty as to complain about that, unless they want employees to scream their ears off.