It depends on what you want really.
I have done brunch in many ways some examples would be
Do a full fry up so sausage Bacon, eggs, black pudding, hash browns, beans, tomatoes, mushrooms toast etc and have it all in dishes dor people to help themselves.
Another that I do is greek yogurt and berries with honey followed by
Bagels with smoked salmon and cream cheese. You can substitute that salmon for bacon or ham.
A selection of croissants, bagels, Crumpets, Pancakes, English muffins with good butter, a couple of jams and a nice marmalade maybe with some honey, chocolate spread etc. Served with a large fruit salad.
Avocado toast with, salmon, and poached eggs or pesto eggs served on lightky toasted sourdough followed by yogurt and berries.
A good selection of sweet pastries like Danish, brioche etc.
Good proper coffee in a french press and good tea. Also I include herbal teas.
Fresh fruit juices.
We aren't big drinkers but would have some fizz for special occasions
Just a few suggestions but the best thing about brunch is that it is so very flexible.