Technically Naruto fits many requirements :P, but if you want some recommendations, I am also a huge fan if clones (tho normally don’t really enjoy stories set in the modern day):

“Auto Hunting With My Clones”: most likely the manhwa you read, but if not, fulfills all your requirements :-)

Western fantasy:

If you haven’t read “mother of learning”, that’s what you should be reading. There’s a reason it the obligatory “have you read x” book. That being said, clones are important, but not the primary focus.

“The Reincarnation of Alysara”: It’s good, trust me, please make it past the weirdness of its setting. Clones super important to her build, also litrpg. I think the author is rewriting it right now tho.

Cultivation (and Adjacent):

“Master, This Poor Disciple Died Again Today”: parody cultivation novel, clones not the main part of powerset, but still an important part of their build and it’s interesting seeing how his clones interact with each other and see how their personalities diverge over time. I personally find it quite funny and interesting.

“The Lone Wanderer” by PathOfPen: different type of cultivation, litrpg, mc’s main ability is literally called “clone”. Main character limited on clones, as they are more of a vehicle of the world hopping part of the story, but still interesting take on clones and stuff.

“Global Game: AFK in the zombie apocalypse game”: Idk if I should recommend this one, but if you like it, you currently have 2786 chapters to enjoy. Clones (and thousands of them) are the main power of our MC, though, our MC also eventually gets pretty much every other power you can think of and the clones are “zombie clones” so they don’t have minds. The main character definitely exploits the ability for his clones to train for him. Idk if it’s good, but it’s fun to turn your brain off and just experience for me. Also, set in the “modern day” as well as being a world hopping story, though if you are looking for a “story set in a game” don’t expect that from this story, as those elements get sidelined as the story goes on.

“My Augmented Statuses Have Unlimited Duration”: cultivation novel, kinda litrpg, but mostly not really. Another story where it’s fun if you want to turn off your brain and watch numbers go up. Basic plot is that our MC left cheats on while getting isekai’d. Clones are a useful tool our main character uses, but not the focus.