Two cases:
A small shop has three company holidays identical to the communal school holidays in winter, spring and autumn and the last two weeks of summer holiday.
A bakery has Opening houers that are also open on holidays except between xmas and new year where they have closed.
Depending on which editor you use, the opening hours usually have a value entry editor that allows you to define: Closed on school holidays opening_hours=...; SH off → closed during school holidays
It can be used together with PH (public holidays) if that’s the case Different hours and days during school holidays opening_hours=...; SH Mo-Sa 09:00-12:00 → open monday to saturday 9:00 to 12:00 during school holidays, as an exception to regular schedule
Now to your specific scenario:
Regarding the small shop, if it’s just those three days and not every SH day and those three days are not subject to change (e.g. “Dec 25th” and “first Sunday of November” are not subject to change) you could add them explicitly as off days. Otherwise I would approximate to SH off and maybe write a description or use text form for complex situations;
Regarding the bakery, I would write Dec 25 - Jan 1 off in addition to the regular opening hours.