From the Accompaniment Styles menu, choose from:
Jazz - Latin/Swing
Jazz - Swing Two/Four
Jazz - Bossa/Swing (iReal Pro v2021.4 or higher)
(where the playback style changes between the A and B sections)

Our Jazz - Ballad Double-time feel - plays ballad feel for the first and last choruses, but changes to double time in the middle repeats.

We are working on adding more styles.

Workarounds
1 Two individual styles cannot be switched to another during a song.
However you can use an Audio editor or DAW to sequentially sequence the different sections of a song or each repeat of the song with different styles. Share (export) the audio file of the song separately with the different playback styles of the song you require. Import into your audio editor and create your backing track from the different exports as required (using slice, trim, cut, copy, paste etc.) and render the resulting audio file for your practice or performance.

2 To keep the song switching at every chorus throughout the song as it plays through, make sure that there are no repeated sections (you might need to write out repeated sections) then put an opening repeat at the first measure and a closing repeat at the last one, (in other words, repeat the entire song). Add a text indication at the end of the chart (at the last measure) of how many times you want the song to be repeated for example x5 and then set the player to one chorus (1 repeat).
Since the player believes you are now in the first (or last) chorus it will keep switching styles for all 5 repeats.