What SEO settings do I have?

You can add Meta keywords and Meta description to rank better and help more users discover your site. You can also save custom header and body scripts. Please do this from Settings > Custom scripts

How do I leverage Google Analytics?

You can register for a Google Analytics account and add the identifier code in the admin console to start utilizing the statistical and analytical advantage it provides to help make smart decisions to increase site performance across different metrics. Do this from Settings > SEO Analytics.

Is there a way to place to google  Tag Manager ID

Yes, there is a google tag manager,

This allows the owner to manage all website tracking tags (e.g., Google Analytics, Google Ads, Facebook Pixel) from a single, easy-to-use interface without needing to repeatedly edit the website’s source code.