Can't say for sure that it's still good but if you want to do it once without installing a program and fiddling around with all the settings then that should probably work just fine.
Otherwise calibre offers a very feature rich ebook conversion tool but goddamn do I only understand half of the functions in that app. Still it's by far the most powerful and feature rich app for ebooks.
It's been a long time since I've used this tool but it used to be very good:
https://www.ilovepdf.com.cn/en/convert/epub-to-pdf/
Can't say for sure that it's still good but if you want to do it once without installing a program and fiddling around with all the settings then that should probably work just fine.
Otherwise calibre offers a very feature rich ebook conversion tool but goddamn do I only understand half of the functions in that app. Still it's by far the most powerful and feature rich app for ebooks.