How to render novel view synthesis as any pose (the extrinsic matrix output pose is different with the extrinsic matrix input pose when training)?

Hello!

I would like to thank you for this very interesting work, I'm reading the paper and code as they have very interesting ideas.
But I want to ask how can I render the novel view with any extrinsic matrix I want ? And how can I use file weight .pth after I training this to render any view?
Thanks a lot. 