Read these two in this specific order, tho not a sequel they're connected, also don't be put off by the art at the start, it changes for the better in just a few chapters :
Song of Reverberation
https://www.mangago.zone/read-manga/song_of_reverberation/
The Promise
https://www.mangago.zone/read-manga/the_promise/
https://www.mangago.zone/read-manga/a_trace_of_the_wonder/ 100% I can't remember the webtoon but the novel is a little nsfw.
If you have time and really want a good incredible world building I HIGHLY recommend Turning. Its a slowburn and omegaverse though its not the main theme at all, main tags are second life, time travel, action, found family, politics and romance. It is nsfw too but it takes a long time before anything happens. Before committing to the long novel you might want to see if you find the manhwa interesting enough. https://www.mangago.zone/read-manga/turning/ probably the best korean novel i have ever read, I will always recommend it to everyone but as it is long and has an extensive world building, not a lot of people are willing to commit to it haha
READ ETERNAL COVENANT ITS PEAK https://www.mangago.zone/read-manga/eternal_covenant/
recs like https://www.mangago.zone/read-manga/the_hunter_s_gonna_lay_low/ ? pls
novels are highly welcomed as well, preferably shounen/shoujo ai and something that puts lots of effort in world building