How enforced are underage drinking laws?

Hello, today I posted this post on a Scotland subreddit, and found out that drinking laws have tightened up, so I was wondering if they've gotten stricter in Ireland? I am 16 and currently visiting Edinburgh, but plan to also go to Dublin and Belfast. I went to Ireland last year, and they were very laid back about drinking, never got ID'd and was even offered drinks multiple times, with my parents present of course.

So in summary, will I be able to drink in Ireland? And is it stricter in Northern Ireland?