Since you need to automatically apply a sensitivity label to resumes based on their content and structure (work experience, education, accomplishments), a trainable classifier is the best choice.
Trainable classifiers use machine learning to identify unstructured data, such as resumes, contracts, or legal documents. Instead of relying on predefined patterns (like keywords or regular expressions), a trainable classifier learns from sample documents and can accurately identify resumes even if they are formatted differently.
Final Approach:
# Train a trainable classifier using sample resumes.
# Deploy the classifier in Microsoft Purview.
# Configure a sensitivity label to be automatically applied when a document matches the classifier.