Try this link, , https://www.irs.gov/submit-power-of-attorney-and-tax-information-authorizations You use form 8821 to receive your clients transcript, or have your client request the transcript him/her self.

You meant is not there any availability through ONLINE from IRS account, right?

Sorry, but I am not sure what your asking

I meant, we can not find 1040-X transcript in here: https://www.irs.gov/payments/your-online-account

Am I right?

The IRS does not have transcript for 1040-X but just the original 1040. The record transcript has information on 10400-X filed, additional tax paid or refund received.