Check out the size map in UE5 it helped me trim down my file a bunch, by highlighting my biggest problem assets.
https://dev.epicgames.com/community/learning/tutorials/r4y7/unreal-engine-size-m...
Usually, you can only do so much, other than remove unused assets (especially out of starter content if you import that in your project) but you could potentially retopologize some of the heavier assets with Blender, and I believe there are some options for compressing sound files and the way unreal packages the project assets up in the final build, but I haven't figured out how that all works yet.