Your next destination is Los Platos, a small town to the north of the lighthouse. It takes you through South Province (Area One).
However, there’s quite a lot for you to explore in the area past the lighthouse. A lot of it is optional, though. There are also a few Trainers for you to battle in the area, but they’re all optional and they won’t challenge you unless you talk to them, unlike older games where they would stop you if you crossed their path.
Getting to Los Platos is pretty easy: just follow the path and head north.
There’s a river with a bridge crossing it. If you follow the river to the east, you’ll eventually reach the sea, but there are some interesting Pokémon out along that way such as Wiglett, Wingull, and Magikarp.
Head up the hills to the east and keep going along that path to find some small lakes. There are some more useful Pokémon around here, such as Flamigo, Paldean Wooper, and possibly Chewtle. Flamigo in particular is a very good Pokémon due to having stats equivalent to a fully-evolved Pokémon, as it doesn’t evolve—it’s a great Flying/Fighting-type Pokémon, although doesn’t get the best of moves early on.
There are also some ruins over there which have a few Pokémon like Drowzee around them, and some items.
Anyway, explore however much of the surrounding area as you’d like, then make your way to Los Platos when you’re done.