Of course there's always a bit of "fear of the unknown" when traveling in a new place and especially one of Europe's largest train stations. However, rest assured that Termini is fairly easy to navigate, especially if you've already experienced large stations such as Paris and London.
Termini was recently ranked 4th among the Top 10 Most Passenger-Friendly European Railway Stations 2022.25
It's a two-level station with plenty of shopping to enjoy, and the tracks are well-signed and easy to reach. If you've already traveled by train in Europe, you'll have nothing to worry about. Even for a first-timer, Termini is a fairly easy station to get around. I think the best thing for curbing travel anxiety is just to allow yourself plenty of extra time.