Competence and evaluation of auditors – ISO 19011:2018
ISO 19011:2018 7.3: Establishing auditor evaluation criteria
Guidance: evaluation criteria should include qualitative ones (for example behaviour, knowledge or skills shown during training or at work) and quantitative ones (for example how many years of education and work experience a person has, how many audits they have carried out, and how many hours of audit training they have had).
This control maps to 13 controls across 8 other frameworks. If you already hold one of them, the evidence you collected for it is the starting point here rather than new work.