Sadly, at this stage, the chances of recovery are slim but not totally lost.
Since the fish is no longer eating, you would need to use an antibiotic which is absorbed through the skin and gills. If the Ph of your water is 7.0 or higher, Kanaplex would be the best choice for this. If your Ph is under 7.0, nitrofuracin green and Neomycin are better at the lower Ph. This article (
https://www.aquarium-pond-answers.com/2006/11/betta-with-dropsy.html ) has a good description of using a cocktail of medications for this condition but only applies if the cause is bacterial. I say this because if you look at the fish in my avatar, it too suffered from "dropsy" but it's cause was not bacterial. It had swallowed some aquarium gravel which caused a blockage which led to the swelling in the abdomen and eventual death. I only found this out during an autopsy after the fish had died.
Dropsy is a condition best prevented over treated. Usually once the scales create that pinecone effect, the condition is very difficult to correct. As I mentioned, even doing everything correctly, fish can still do things that cause themselves harm ( as my fish did).
On a non emotional aspect, any attempt to cure this fish can become expensive so you need to weigh the cost of treatment over the cost of replacement.
Hope this helps