Identifying external compliance requirements is most likely to occur during COBIT Implementation Phase 2:
Where Are We Now?, because this phase involves assessing the current state of the enterprise's governance and management system, as well as its strengths, weaknesses, opportunities, and threats12. This phase also includes identifying the relevant stakeholders, drivers, and scope of the implementation program . Therefore, this phase requires a thorough understanding of the external laws, regulations, and contractual obligations that apply to the enterprise and its I&T activities.
References: 1: COBIT 2019 Implementation Guide 2: COBIT 2019 Implementation - ISACA : Connecting COBIT 2019 to the NIST Cybersecurity Framework - ISACA : 7 Phases of COBIT Implementation:
Explained - The Knowledge Academy : Compliance with External Requirements - Morland-Austin