No, not really, because it’s part of what windows does. It is technically possible to use a so-called icon overlay, but it has never worked very well and requires a lot of very specific code for Windows.
The only way would be to place the suffix before the final extension, as below;
Windows will interpret the .txt extension and show a Notepad icon. AxCrypt could then intercept anything with .axx before the final part of the extension providing you manually opened the AxCrypt application.
The problem with this method is that you’d lose the ‘click to open’ ability in AxCrypt and the file would load in the native application which risks damaging it because you’d be editing encrypted material.
That’s the main reason such a method hasn’t been implemented.