Iran Sanctions Relief Review Act of 2021 This bill restricts the President's authority to unilaterally undertake certain actions with respect to Iran and increases congressional oversight of those actions. Specifically, the President must report to Congress before terminating or waiving sanctions related to Iran or taking a licensing action that significantly alters U.S. foreign policy with respect to Iran. Each report must (1) describe the proposed action and its rationale, and (2) indicate whether or not the action is intended to significantly alter foreign policy concerning Iran. If the intention is to alter that policy, the report must provide additional information about the policy objectives and anticipated effects of the action. After the President submits a report, the bill provides Congress with a 30-day period to review it; this period is extended to 60 days for reports submitted between July 10 and September 7. During this period, Congress may enact a joint resolution approving or disapproving the action. During the review period, the President may not take the action unless Congress passes a joint resolution of approval; if Congress enacts a joint resolution of disapproval, the bill prohibits the President from taking the action. The bill also outlines procedures for the introduction and consideration of these types of joint resolutions.