You have two options. Connect the Arc to your display via eARC and then set the Play 3’s as the surround speakers. This is the recommended method.
Or
Setup the Arc to your display and then have the Play 3s setup as a separate room in the Sonos App and then when TV audio is playing through the ARC then you would group in the Play 3s. Be aware that this method is designed for speakers that are physically located in different rooms, when you group them to play TV audio and they are actually in the same room you will hear a delay.