Easy but whacky:
Use the “Generate identity profile preview” API: generate-identity-preview | SailPoint Developer Community
In the HTTP Action call / payload, you can define a dummy transform definition, on the fly, that contains your date transform. Provide it with an explicit input date string (i.e. it doesn’t need to touch any identity attribute or any account attribute). The preview returned will be the post-transformed output.
Kind of abusing the API….but it technically does exactly what it’s coded to do.
This approach also gives you access to Velocity Template evaluation (static Transform) to things such as list element manipulation.