Yes. Fanfiction.net might also have some. Look for stories with high ratings and a lot of reviews. The stories could range from cute and fluffy where Wonho and the reader share innocent moments like going on a coffee date, to more angsty ones where there are misunderstandings or obstacles in their relationship. It really depends on what kind of story you're into.
Tumblr can be a source too. There are some blogs dedicated to sharing Monsta X fanfiction. Just search for 'Monsta X Wonho x Reader' in the Tumblr search bar. However, the quality might vary more compared to AO3. But you might find some hidden gems that are really creative and unique in their portrayal of the relationship between Wonho and the reader.
One great place to find Monsta X Wonho x Reader fanfiction is Archive of Our Own (AO3). There are many well - written stories there. You can search by tags like 'Monsta X', 'Wonho' and 'Reader - Insert' to narrow down the results. Some popular ones often involve sweet romantic scenarios between the reader and Wonho, set in various fictional situations like a music video - inspired world or a college campus.