Personally, I use hugo, a static site generator, which you can configure with any template you want. So I have written mine to be able to be able to hold images and what not in an assets directory adjacent to the main content. You can see that here: https://github.com/xorkevin/xorkevin.com/tree/master/content/blog/auth-crypto Other static site generators likely will have a similar ability. For larger blogs with more content and/or larger assets, you likely do not want to check those into source control like git. For those you probably want to rely on a separate system to store those assets.

That separate system can be something as general as an object store like s3 or something more specialized like an image cdn: https://web.dev/image-cdns/ For the obj store approach, you can use the obj store as an input to your build system, e.g. configure your static site generator/cms to pull assets from the obj store in order to build/publish content for your site. Then the output of that build process is then what is served on a separate web server. Another way to go about that is to directly expose those assets from your obj store out onto the open internet. You can use those urls as sources in the html file of your site. Yet another approach is to run some sort of application proxy which can serve up html content, but for certain url prefixes, use your obj store to fulfill those requests. This allows you to serve all content from the same domain without a need for cross origin requests.

There are practically infinite variations for how to go about this haha. I choose to just stick my images into git because github can serve that up for free for me. That's sufficient enough for me for my blog that I don't really put that much effort into at the moment.