You might need to clarify ‘side wall positioning’, but pretty sure the answer is no. You will likely need to fin some other generic mount or get something custom made if you want mount Era 300s on a wall, but tilted 90 degrees to be perpendicular to the wall. Sonos site says these can swivel 15%.
Such a mount as your describing would stick out around 18 inches from the wall.
Thank you kind Sir. I thought this would be a problem, my armchair is fairly close to the wall and angled towards the tv, my RH old play 1 was behind about 2 foot and this is the ONLY place I could put the Era300 wall mounts. If they only ‘swivel 15 degrees they would be facing the centre of the room duh…back to the drawing board…… possibly have to have stands but they are not cheap.
Thanks again