How many people are usually on a guided tour group?

Just booked an Egypt tour and realized I never asked about group size. The website says “small group” but doesn’t give an exact number. I’ve seen some tours advertised as 8 to 12 people and others that go up to 40+.

What’s typical for a multi-day guided tour? And does the group size actually matter for the experience? I feel like 40 people on a bus would be really different from 15. We’re in our early 60s and don’t want to feel like we’re on a school field trip.