Hey Taylor! Welcome to Windows Central. What do you mean by this? Are you looking to test new phones themselves, OR to test new version of the Windows Mobile OS?
If it's phones, it's unlikely as most of that testing is done by professionals, such as Microsoft themselves, cellular carrier employees, and perhaps some tech insiders. Also I'm not sure how much testing goes on for Microsoft phones since the OS is struggling.
Ok for testing with Microsoft for software, info here....