Heart of Portugal tour

If it not listed in the itinerary, then it's probably not included. Once you register for a tour, you'll receive an email with instructions to create a 'tour account.' The tour account has a button to 'manage tour.' Once inside your tour, you'll see tabs titled Overview, Payment, Pre-tour Planning, COVID, Tour Kit, Itinerary, and Documents. Check under the Pre-tour Planning tab to see what's recommended.

From what I've read of Sintra, it requires a whole day. I believe it's at least an hour and a half travel time to get there, plus visiting the buildings and gardens would take a lot of time. It might be best to do this prior to the tour starting. https://www.parquesdesintra.pt/en/plan-your-visit/itineraries/sintra-by-foot/

A few of our Heart of Portugal tour mates had visited Sintra prior to the tour. It doesn't seem feasible to do it on the Day 2 free afternoon unless, perhaps, you're going to skip the group's evening activity that day, dinner with a fado performance. But don't miss that! Among all the wonderful group meal experiences of the tour, that one was a real highlight. The dinner is in Casa de Alentejo, built in the 1600's, a former residence of viscounts. Very unassuming on the outside, once you're in you're stunned by the beauty, the huge, ornate interior courtyard built in the Moorish style, the former ballroom where our meal took place, decorated in Louis XVI style. Our performers were two young women who were students being professionally trained in fado performance and I was awed by their beautiful voices. The guitarist who accompanied them was outstanding too. You'll attend a second performance of live fado later in the tour (Coimbra) but Lisbon and Coimbra have two completely different styles of fado. It's fun to experience both.

I went to Sintra after the tour ended in Porto. I stayed in Sintra for 3 nights, then took an Uber to the Lisbon airport which is less than an hour from Sintra.