If you go for a late breakfast or late lunch it isn’t that hard to do. Three weeks ago I had a 4 hour lunch date with a friend I haven’t seen in a while. It was a deli, you go to the counter order your food and bring your food to the table. If they had run out of tables we would have left in respect for other patrons, but it never got to that point.
When I was a teenager we sometimes hung out at fast food, pizza, and other restaurants for hours. It was usually odd hours like after school from 3:00 to 5:00, things like that, and there could be a menu change.
Now, my SIL, when she got married the first time her reception served dinner very late at night, and then breakfast in the morning. Partied all night.