Set volume when using announce option for media players

The new Announce option for the media_player.play_media service is really awesome, I’ve always had struggles getting this to work properly before.
However, I would like to control the volume of the announcement itself, our Heos system seems to play the announcements at a very low volume compared to the music we have playing.

is it possible to use volume level in the media_player.play_media option?