I am now retired but worked at pretty senior level .
it is about vocal unapologetic boundaries
I was very fortunate to have a senior male director, early in my career, who always left work at 4pm on dot. He collected his kids, went home, did chores, tea, bath and bedtime. It was extreme exceptions he bent his rule. He blocked his diary and that was it. Have to say next day his (remember this is old school 1990s) his secretary was inundated with typing as he’d work for an hour or two form home in evenings if needed
no one ever questioned it - ever. There was a sort of admiration at his rigid boundary
when I had kids, I left on time. Booked my diary out . Refused meetings. Stated clearly and loudly I had nursery/school timelines to meet. But again I’d work in evenings at time. I “banked” huge quantities of good will and commitment when I could and when it was needed and as kids got older I put more hours in if needed. My general rules were rigid, but they knew I could flex at times of peak demand or for travel etc. by time kids were in secondary school no one would ever, ever dare to question me leaving mid afternoon for a school event, or come in late, or stay working at home with sick kid.
the trick is to bank goodwill and commitment as and when you can. It works both ways. Have a strict rule, but make it clear you will only break the rule when there is a genuine need, and if there is you will step up to support the business.
I always had in back of mind, if my boss, all those years back could do it, and be successful, so could I …just had to figure out how to earn that reputation for flexibility whilst being inflexible generally. Clear boundaries. No apology.