Hola! The RS guidebook, at least as of 2019, says that if you book the tour of the Cathedral rooftop you may also tour the inside of the Cathedral itself. This is no longer the case. I tried at two entrances, just to make sure I wasn’t being misunderstood. After the rooftop tour, the guide confirmed that this had changed and you must buy another ticket to tour the inside.
The rooftop tour is worth the money and effort. The view of Sevilla is amazing. There are some tight spiral stairs and a few awkward steps. Also, to get to the stairs that get you to the roof you will see a bit of the inside.
As of yesterday tickets to the inside were still available, but I couldn’t get the website to work on my phone for online purchase.
Hope this helps.