Hello everyone Is it Possible to extend the Account.Model.js Suitescript File? I need to make some changes to the registration function, or Do I need to overwrite it?

Depending on your SCA version, there is best practice of extending. But to answer your question, yes you can and extending is the best route imho.

Simply extend the SS model`AccountModel.extend({})` and use it from your front-end model. P.S. Front-end (F) and Back-end (B) models have different extending mechanisms like the F model returns the function whereas the B model returns the object.

The best practice depends on what version of the product you are running.