We just did that couple of weeks ago, was able to reduce packaged zipped file from 170MB to 90MB. There are two things: engine content and your content.
For reducing engine content we use settings like in attached pic: configuration set to shipping,
full rebuild, for distribution, no debug files, use pak file, don’t include prerequisites, don’t include crash reporter, cook only maps, compressed packages and don’t include editor content. Then add your maps in list of maps (we had only one map).
Also, in Edit>Plugins menu you can disable all plugins which you are not using.
For your content, right click on your map and choose “Size map”. It shows you what will be included with the map. You can see if there are some unnecessarily large textures, or something not really used or something like that. For example, we had huge 4k textures that was only used as defaults for some materials, then replaced by something else in the instanced materials. If you don’t understand why some asset is here you can right click on this asset in the browser and choose reference viewer, it will show you who is using this asset.
Another thing we did, just for clean things up, is to create a new empty project and migrate the maps to this new project. That will move the maps and all dependencies, but not unused stuff. Then copy the content folder from the new project back to your old project (rename your old content folder first, so you will not lose anything).