I don't think there is one. Depending on how serious you're trying to be, you might try a natural falsetto (really high pitch, with a learned technique and practice to make it work well), or look for things that do the job completely outside of OBS. For the latter, the question then becomes, "How to get audio from the output of one app to the input of another?"
Or maybe you could recruit or hire a voice actress? Doesn't have to be a union member from the formal industry, just someone who can read the lines into a mic, with the right enthusiasm to be believable in the final product.
