I haven't looked for one, but my best suggestion would be to search either The WordPress Plugins Repository
or or use Google
for something like "WordPress appointment scheduling plugin". That's the same thing I would end up doing.
For any plugin you find in the repository, make sure you check out the "screenshots" tab of the repository page to get an idea of what it looks like before you install it, that way you don't waste time installing something you don't like.