You probably cannot convert .grd file (gradient) to .asl files (layer styles) in Adobe Photoshop. However, when working with pictures in the program you may possible apply the gradients and generate the styles should you need it. But it is not a conversion in proper sense.
Convert Adobe Photoshop gradient preset to Adobe Photoshop layer style.
We found 2 software records in the database related to .grd to .asl file format conversion.
Microsoft Windows software - convert grd to asl on Windows
One of the best bitmap graphic editing program
Convert from grd file format
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned grd to asl. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
Apple macOS / Mac OS X software - convert grd to asl on OS X
Mac version of popular digital image editor