I'd recommend 'Tower of God'. It shares the theme of characters climbing through challenging levels and developing their abilities, similar to Solo Levelling. The world-building and character growth are quite engaging.
Well, the 'solo levelling novel' tells the tale of an underdog. In this world, hunters are tasked with protecting humanity from the threats that come out of these mysterious gates. Our main character was once a very weak hunter. But he discovers a unique ability that allows him to gain power at an extraordinary rate. As he levels up solo, without relying much on a team, he has to deal with not only the physical threats of the monsters but also the envy and suspicion of other hunters. His story is one of growth, self - discovery, and the pursuit of true strength in a dangerous world filled with both magic and mayhem.
It's about a world where hunters fight against monsters. The protagonist starts as a very weak hunter but gradually becomes extremely powerful through various challenges and adventures.