Iam mocking some data .In response for current date iam using regular expression {{now formate yyyyMMdd}} if i want to add 3 days to the current date can i know regular expression for future date.

You can use

offset

to change the date

{{now offset='3 days' format='yyyyMMdd'}}

https://wiremock.org/docs/response-templating/#date-and-time-helpers

@Aaron is right. While you can technically do it with regex it's unlikely something you want