After you have traveled a bit, you figure out that there are 2 types of stations in Europe, Through stations and a few Terminal type stations in big cities. Germans being German, they have very nice detailed diagrams of all larger stations available on the internet. Italians are like "Who needs all that information? All the stations are the same except for the number of tracks." So here is a diagram for a typical Through station, in this case, Munich-Pasing, a larger suburban station.
https://www.bahnhof.de/resource/blob/1022986/1bcf122688ffd20b72af4cf5956b9fe2/M%C3%BCnchen-Pasing_locationpdf-data.pdf
Note that this has 9 tracks numbered 2-10, (no No 1), ganged into 4 platforms with tracks on each side, and a side platform usually next to the station building. Underneath at ground level is the cross-over tunnel that connects via a stairway all the platforms to the main station building, where the ticket office is located along with rest rooms, businesses that sell things travelers need, like snacks, drinks, newspapers etc. So if you are connecting from a train that arrives on Track 9 to a train departing from Track 4, you get off, go down the stairs to the cross-over tunnel, walk a little ways to the stairway marked Tracks 3 & 4, walk up the stairs to the new platform and board your connecting train. You can see that should only take a couple of minutes. Some stations like this one have stairs, ramps, escalators, and even elevators. Don't count on elevators and escalators in Italy. Also, if the tracks are at ground level or underground, they have an overhead bridge instead of a tunnel. 99% of all the thousands of stations look similar to this one.
For big city Terminal stations, the layout is similar to this one, Munich Hauptbahnhof.
https://www.bahnhof.de/resource/blob/1023016/dd3779fe2eb8ca99bf71edb992320abd/M%C3%BCnchen-Hbf_locationPdf-data.pdf
This one has 32 tracks numbered 5-36, all on the same level. You don't have to go up or down any stairs. Nonetheless, it is obvious that changing trains at one of these stations can take longer, especially if you are in the last car of the train and have to walk the entire length of the train to get to the platform head, then along the platform head to your new track, then out to your assigned car if you have a seat reservation. And changing here from Track 6 to Track 32 is a long walk.
So for your stations, Florence Santa Maria Novella, Rome Termini, and Venice Santa Lucia are all Terminal stations. All the other ones are Through stations.