Where can I set the "Cache-Control" or "ETag" headers for my website?

My website has a cache problem where my ETag's aren't getting generated correctly when a change is made to my website.

I've searched all over the internet, and there are tons of resources explaining WHAT the "ETag" header is for, but there's almost nothing explaining WHERE to set it.

Is there some configuration file I put it in? Some articles mentioned setting ETag generation rules in the .htaccess file, but isn't that just for Apache servers?

Any help is appreciated.

My web app is built with webpack, contained with Docker, and hosted with Kubernetes (using an nginx ingress server).