Specify content to protect when scaling

1. Make a selection around the content you want to protect and then, in the Channels panel, click Save Selection As Channel .
2. (Optional) Choose Select > All if you’re scaling a Background layer.
3. Choose Edit > Content-Aware Scale.
4. In the options bar, choose the alpha channel you created.
5. Drag a handle on the bounding border to scale the image.

 community help (adobe.com)