Filters -> Combine -> Depth Merge
Unfortunately, this is a compiled plugin and the preview size is set in the code. It is not possible to change it from within Gimp.
Made for an earlier era when images were much smaller. I had a quick look around for a more recent alternative, nothing so far. Maybe someone will come up with a recommendation.
edit: You could try the gmic plugin http://www.gmic.eu
Several blending filters but nothing with the depth-map option. example: https://i.imgur.com/Gi7OIoP.jpg
Unfortunately, this is a compiled plugin and the preview size is set in the code. It is not possible to change it from within Gimp.
Made for an earlier era when images were much smaller. I had a quick look around for a more recent alternative, nothing so far. Maybe someone will come up with a recommendation.
edit: You could try the gmic plugin http://www.gmic.eu
Several blending filters but nothing with the depth-map option. example: https://i.imgur.com/Gi7OIoP.jpg