An underdog - to - overpowered protagonist arc. 'Solo Leveling' shows the journey of a weak character becoming extremely powerful. 'That Time I Got Reincarnated as a Slime' also follows this pattern. The slime starts as a weak entity but through various means, it becomes a very powerful being in its world, which is a characteristic shared with 'Solo Leveling'.
Sure was! Solo Leveling began as a novel and gained popularity, which led to its adaptation into various mediums. The novel laid the foundation for the story and characters that fans came to love.