You can group the Play:1s with the Playbar in the Sonos app to play the same audio out of all the speakers at the same time. Streaming music will be in sync, but playing TV audio will have a slight delay from the Play:1s compared to the Playbar. Read more here:

https://support.sonos.com/en-us/article/group-and-ungroup-rooms

You can also add two of the Play:1s as surrounds to the Playbar where they will act as rear left and rear right surround speakers. Read more here:

https://support.sonos.com/en-us/article/add-surround-speakers-to-a-sonos-home-theater