How to get refund after cancelling my free trial on CamScanner?

That will be up to Apple Support.

Request a refund for apps or content that you bought from Apple - Apple Support

You must cancel a free trial at least 24 hours before the end. Otherwise, the trial automatically converts to a subscription as per the free trial terms and conditions you agreed to.

Please follow the steps in the Apple Support article I linked below to cancel your subscription.

If you want to cancel a subscription from Apple - Apple Support

Subscriptions and Billing - Official Apple Support

shraddha180 wrote:

Hi thanks for your advice is it possible to get the refund

All you can do is try using the provided link. Remember you did agree to the subscription price if you did not cancel before the trial period ends. The free trial is only for that period of time that was specified. For example, if the free trial was for 1 week, you don't get to extend the free trial for 2 weeks by cancelling and then requesting a refund. I would not expect a refund, but in some cases Apple has granted a compassionate refund.