It is possible to convert an Ogg Vorbis audio file to MP3 using an audio converter. There are a number of such converters, but my favourite one is, as usual, FreeRIP. FreeRIP can convert Ogg Vorbis files to a number of different formats, such like FLAC, WMA, WAV and, of course, MP3.

Just please note that being both Ogg Vorbis and MP3 lossy compression schemes, you will get some loss in quality.