I can audit your image SEO, but not from a description of the site, and not for thousands of images at once without a list. I need:
- Image list (required). Per image: the page it is on, filename, alt text, whether it is an img tag or a CSS background, its loading attribute, and whether it is visible on first load (first viewport). A crawler image export plus your notes on first viewport works. If thousands is too many, start with your key templates, for example one product page and one category page.
- LCP element (optional): if you or your developer already know which element is the LCP element on each page, tell me. My sources do not say which tool reports it, so I will not point you to one. Default if missing: I use your first viewport column only and mark LCP as not known.
On "lazy loading everything": web.dev advises images visible on first load, especially LCP images, use the browser's default eager loading. Google's lazy loading guidance asks that content load when it is "visible in the viewport". So I will flag lazy loading on first viewport images and leave the rest alone; it is a question to settle with your developer using your data, not a blanket rule from me.
I will not edit pages, templates or your media library; I will return a fix list for your approval.