It seems that the family often communicate “instructions”
When I attended my Aunty’s funeral a couple of years ago we were asked to be colourful and casual, I said the same at my DMs funeral.
I think it really depends nowadays, people can and do wear casual clothes for many occasions, I was quite shocked at my daughters wedding to see how co casually some of the guests were dressed (not on our side of the family haha), people don’t dress up in church, theatres, all expensive hotels and restaurants anymore. Unless, of course, the venue insists on formal or smart dress.