I don't know where you could share your ideas to get an artist here but you could probably write up the story and post on something like wattpad so you could reach out to more people and hopefully in the process, find someone willing to turn it into a manga. Either way, good luck with it.
Hello hellooo thanks for offering your ideas! I'm not an artist myself, but I've joined a small group in the hopes of doing the same - contribute my storyline idea to turn it into a manga. You might wanna check this post, op sent in the replies the discord link: https://www.mangago.zone/home/mangatopic/17303186/
So I dont know if this is an option I am not great at drawing anything really lol but I am really good with coming up with storyline ideas for smut manga I didnt know if there was a page on here I could offer my ideas on so someone with the artistic ability could bring my ideas to life. I wouldnt claim them or ask for profit nothing like that. Just want to share my ideas is all. Thanks