Believe it or not, that sadly not always the case. My son's dad's family will have family get togethers and literally serve *nothing* plant-wise. He has learned to bring his own food. ...When I first met the family years ago, my ex-SIL was overly accommodating... Always asking me what I was going to eat, making sure there was something. Then one day she just stopped. It was Thanksgiving or Xmas or NYE or something - we drove the 1.5 hours to get there and *everything* they served had meat in it.
Everything! (I was pescatarian at the time and there was
still literally nothing I could eat - I believe the put bacon in the mashed potatoes. Ugh.) Dad was over 300 lbs, SIL to be ended up with I think 2 stints --- They were huge wine connoisseurs and hosted wine tasting parties with cheese galore ALL the time. They built a large wine cellar even in their family room. Like, it was a small walk-in "fridge." Dad is no longer alive, ex-SIL hasn't changed at all. And sadly, neither has my son's dad. I bought Dr. Greger's 'How Not To Die' book for my son to give him for his birthday or Xmas or something... He will never be one who will say "no" to whatever the norm is in his family, and they will never change. (And their father died in the hospital having carotid artery surgery to remove the plaque buildup.) It's very sad, to tell the truth.
Always be prepared to bring your own food, or eat beforehand. That's what I do.