If your file has a separate subtitle track (stream 0:s:0 ), you can overlay it onto the video during the export.
ffmpeg -i "Rick.and.Morty.S01E06.mp4" -ss 00:15:30 -to 00:17:00 -vn -acodec libmp3lame -q:a 2 "Goodbye_Moonmen.mp3" rick and morty s01e06 ffmpeg
Title: