That’s an excellent question! A lot of physicists spend their careers searching for a so-called ‘theory of everything’ that they think will be able to explain everything about the universe, but many other people do think that there will always be something more to learn.
Personally, I think there will always be more to discover. The universe is so unimaginably vast, I can’t imagine we’ll ever know everything.
From my own experience in science, I find that every time I learn a new fact, I also think up a dozen new questions. I think more knowledge will always lead us to more questions, and I don’t think that will ever stop!
Part of me really wants that to be the case. So we can just sit back on a comfy chair, having discovered everything, like ahhh. But I think the question is, even if we have discovered everything, how will we know? One of the issues we face at my job is the unknown unknowns! At least if we know what we don’t know… then we can try and know it… You know?