If you go up in the tower, you do it first, then see the "temple," as they call it. Does anyone know, who has been there, how long they let you stay in the church and wonder around after you saw the tower? Is there a time limit? Can you stay two hours?
We visited in 2016 and there was no time limit.
After going up to the Nativity Tower and walking down we found 2 hrs was about right to wonder around. After we exited we walked the perimeter and then crossed the street to view the amazing facade. It was mesmerizing. https://barcelonalowdown.com/sagrada-familia-tips/
We were there last month. We arrived early in the morning and stayed as long as we wanted, which could have been until closing time.
I second Janis. There is no time limit once you go inside at the time stamped in your ticket.
And to think they're actually getting close to completing the construction first started 140 years ago. Yeaaaaa!
We were there before the pandemic. My wife liked Barcelona so well, she took her daughter back 3 months later.
What you could not do as of 2016 was re-enter the church from the shop, so make sure you visit the shop last. In my experience not very many people go to the museum, which is very interesting. That's a good place to be when the rest of the building gets crowded.
There are two entrances to the church, one was for reservations, the other for walk-ups. You can exit the church to get a good look at the exterior of entrance you didn't use and then go back in to see other parts of the church.