It is part of instructions for Google's assessors to rank sites that fits YMYL category.
You can improve your EAT in the eyes of assessors by:
1. Including Author Names & Biographies for All Editorial Content
2. Invest in Personal Branding (if you are expert in someting and write content by yourself)
3. Cut or Edit Low E-A-T Content (if you have old content, rewrite it with actual information)
4. Get SSL certificate, consider it as investment in technical security
5. If you have opportunity for users yo add their comments or content, then moderate it (check it for EAT before approving).