How can front end devs help improve SEO
Limit the use of H tags (H1, H2, H3, etc) and tags to non-repetitive/important content. Don't use them for content that is repeated throughout the website or across multiple pages, use regualar divs instead.
Use machine-readable fonts as much as possible. If you place text in an image, make sure the alt tag includes the text in the image word-for-word.
Consolidate CSS and JS files and minify them to improve site speed.
Dynamically loading content, or anything that does not come loaded as the page loads, will not get picked up by search engines.