Can I pre-fill value for a custom field on Signup page

Hi Team,

I am trying to read a parameter that is embedded as part of /authorize endpoint and have this value added to the custom signup field (using additionalSignUpFields) so that user no need to re-enter that again while signup.
Suppose the authorize endpoint is /authorize?firstname=“xyz”&screen_hint=signup and when user lands on signup page he should be able to see “xyz” prefilled in the firstname field.

Can you please suggest a way to achieve this.