What Techniques are used for multi-level games and keeping APK size to minimum?

I know about two techniques, one is switching for ARM target only, and the other is deleting unused imported assets, but I feel that since there are many games out there with multiple missions (scenes) and still they run faster than my game and have a size less than 70mb, I maybe missing something else, because I have a game with single scene and it’s already 55MB in size (apk), any other ways to reduce size?

Thank you

There are many techniques you can use. But if you want multiple levels and keep it very small, then consider doing procedural generation of your levels.

Yes if you can generate levels procedurally as @Cornelis-de-Jager suggested it would result in the smallest footprint. However if you prefer to create level by level on your own you can use AssetBundles. You can export assets as well as scenes (which use those assets) as a single assetbundle. AssetBundles can be loaded from external sources on demand at runtime.

For more information see the manual on AssetBundles as well as the AssetBundle class