It's wild how stories stick with you — for 'Solo Leveling' the short version is: yes, the creator wrapped up the story. Chugong finished the original web novel some time before the comic adaptation ended, and the manhwa/webtoon followed through to an official conclusion that the author acknowledged. If you trace the releases, the webtoon serialised its final chapters in late 2021, and those chapters align with the author's intended ending rather than being an abrupt cancellation.
That said, finishing a series doesn't mean there's no more content to enjoy. There are side materials, official artbooks, and translations that fill out the world, plus merchandise and talk of adaptations. The big takeaway for me is comfort — you can read 'Solo Leveling' start-to-finish and feel like you experienced the whole arc as the author meant it, and it leaves a satisfying, if sometimes bittersweet, impression.