In all honesty - YABU to take DC out of school for a holiday, no matter how 'once in a lifetime' it is. For all the many reasons cited by posters already. Even if it has no long term effect on a DC's academic attainment, you're sowing the seeds of 'school isn't really important' in your DC's minds.
But plenty of people do take DC out (and not even for 'once in a lifetime' stuff) so I suspect the OP will go ahead and go for the holiday regardless. You're the parent, after all, so you make the decision.
However - as someone who works in a primary school office - if you do decide to go ahead, please bear in mind the following:
1 The absence will be unauthorised, because the headteacher won't be able to authorise it. Don't send in snotty emails or call the school office in a stinking rage because your precious leave hasn't been authorised. Or call the school office AGAIN in a stinking rage in July when you see a swathe of unauthorised days on your child's school report and you think it is UNFAIR. You are entitled to make a choice as a parent, of course, but you cannot demand that a holiday be authorised or that a school bend over backwards to accommodate you.
2 Chances are, you'll be fined. As per local authority guidelines. Don't send in snotty emails expressing OUTRAGE at the fine or call the school office shouting down the phone expressing outrage at the fine. It's not their fault you decided to go away in term time.
3 Your DC's teacher is not responsible for giving your DC work to do whilst away, nor are they responsible for giving your DC extra work to help them catch up once back. Don't send in snotty emails to the teacher, head of year group or head teacher demanding said work and expressing ABSOLUTE OUTRAGE that teaching staff have not bent over backwards to facilitate your holiday. You made the choice to go away. So you need to deal with that and not get stroppy about it.
Sadly, there appears to be a definite correlation between parents who take their DC out of school in term time and parents who behave as per the above. And it's got worse in the post-Covid 'ultra entitled' period too.
But at the end of the day it's a parent's decision...