Noticed this myself, this would be a welcome addition for sure.

According to DigitalOcean documentation and information from the support team, the Cache-Control headers for static sites on the App Platform are currently fixed to only 10 seconds max-age, and there is no way to change that. This is really inefficient, as it will cause immutable static resources (like images, or JavaScripts/CSS with versioned filenames) to be practically never cached in the browser, leading to many unnecessary reloads.

A simple setting to override this default of only 10 seconds would go a long way towards improving the performance and efficiency of static sites. As a step further, individual resources (e.g. index.html) could have a different max-age for more fine-grained control over caching.