In elementary, like a lot of people here we had to sit with our class but my friend group throughout elementary was pretty big so I always had friends to sit with, and after we finished eating we could go out to play, so the whole group would meet up on the playground afterwards. The first few years of high school, I still sat with my friends from elementary, but I kind of drifted apart from them a bit and grew closer to a different group of friends, so I would move between them - sometimes we all sat together, new and old friends, but grade 11ish onwards I sat with my new friends more.
First year of college I usually ate alone or with a classmate or two if the timing lined up - it's kind of difficult to have the same breaks sometimes in college because everyone has different schedules, but eventually I made friends and we would try to plan our schedules so we could eat lunch together at least a few days a week.
I think I've gotten a lot better at being on my own after graduating high school - I don't mind eating alone now, but as I was always in a big group growing up, the first year of college was tough for me when I didn't have a friend to eat with. Like Rika, sometimes I would actually skip lunch just so I didn't have to sit by myself in a restaurant/cafeteria, but I've gotten over that now and learned to enjoy my alone time.