Consul
Consul automatically converts files when you change their extension on your Mac.
About Consul
Consul turns a familiar Finder action into a quick file conversion workflow. Rename a file with a different extension and the app offers to convert the contents properly instead of merely changing the filename.
It is useful for people who regularly move images, documents, audio, or video between formats and want a lightweight Mac-native shortcut. Conversions stay close to the Finder workflow rather than requiring a separate editor.
Consul is sold as a one-time purchase. Check the developer's site for the current list of supported formats before buying.