Or something that has few or all of the follow tags of kingdom building,isekai/reincarnation, and modern knowledge.
did you read "how realist rebuilt a kingdom"? I don't know if you will enjoy it or not, but it's pretty much like that
Not the same but maybe these: Genjitsushugi Yuusha no Oukoku Saikenki Tensei Shitara Slime Datta Ken Risou no Himo Seikatsu
Trash of the Count’s Family Same relative weak mc with powerfull helpers around him and some scheming
This honestly nothing like RTW. Although Trash is kinda interesting, it's more generic isekai, moreover in a game world. And MC himself becomes strong and fights, as opposed to RTW.
i mean OP wanted " kingdom building,isekai/reincarnation, and modern knowledge" so its not like he suggested boku no pico
Kami Sumeragi Yuusha no Eiyuutan 《Ryokou Tan》 its not a perfect match, but both novels feel quite similar. give a try!