I think Generative Fill would be the way to go in that situation.
Use your tool of choice to select the empy background. I used the Magic Wand tool here, but we don't know what your image looks like.
The Contextual tool bar drop down has an option to expand the selection. It needs to overlap the image by about five pixels.

Click on Generate, then Generate again

And wait with fingers crossed for a good result. It did an OK job in this case.

Note: You can turn on the Contextual Tool Bar from the bottom of the Window menu.
How big is your image? If more than 2000 pixels, it might be better to do it in sections to avoid pixelation.