is there a PC board socket for the 2961257 Phoenix relay
That relay is designed for direct mounting to a PCB, and as such I believe no socket is available.
Based on the PCB layout in the data sheet, I believe this is the type of relay that will fit in a standard machine pin IC socket. Although the pin length is marginal so I wouldn’t use a socket in a high vibration environment.
The exact size would be a22 pin socket however those are expensive due to the unusual pin count.
As long as you don’t mind having two extra pin sockets you can use a much more economical 24 pin socket.