H.265 is not fun. It's resource intensive to decode (to convert), so hopefully you have a faster/newer computer.
You want the software Hybrid
You'll convert H.265 to H.264. Then take the 264 and convert to whatever.
Hybrid isn't overly intuitive. Some guesswork is required. And some intelligent navigating the options. Open, select output type, output name, add to queue, start queue.
I've not had to do this much, but it happens. x265 is too new to be in use, but some people still insist on "newer is better". It makes a smaller file, yes, but "better" is debatable.