The phrase is literally a quotation from the opening oratorio of every episode of the original series, which itself provides phrases repeated in dialogue throughout the franchise. "The final frontier," "these are the voyages," "five-year mission," "to seek out new life and civilizations," "where no man/one has gone before" have all figured in the titles of movies and episodes and have been dropped into dialogue. Doing so is a re-statement of purpose, perhaps to underline the nature of the series and its characters at a given point. It can also point to revivalism or back-to-basics approach, returning to past ideas (whether warranted or not). Despite "strange new worlds" suggesting going to new places, it all references back to the beginning of the franchise. Indeed, ST:SNW is very much a remix show. It introduces few new protagonists and brings back many that are familiar. Some may be a little different from past characterizations, but they are often developing into the well-known characters of the past or they are being filled out, given more motivation by the writing. The setting is presented with greater detail and opulence, but for the most part, they are the same locations: bridge, engineering, mess hall, sick bay, crews' quarters. A whole episode of TOS was revisited by SNW. So "Strange New Worlds" is a perfect title: we're being more adventurous in a way we used to be. And it points to a largely conservative approach, adjusting to contemporary sensibilities but pointing to the past.
(Does Lower Decks do the same? Yes, it is also a remix show that wears meta-narrative on its sleeve. The title does something different than "strange new worlds." It suggests taking the change in perspective from the original episode and making it the cornerstone of the series.)
