I have recently made a small game and its 120mb but when in Unity Under Player Settings I click split binary it does split it but the Apk is 54mb and Obb is 64mb. How can I make the Apk less in size?
I think you apk file contains the data from the first scene,you need to use this plugin
and apply this in your first scene.
The apk when splitting obb files loads into the apk whatever is in the initial scene, so its probably due to the fact that your initial scene is filled up with things. My recommendation would be to have an initial empty scene (probably only a texture that says loading) where you use the obb downloader only, and forwards to your original first project scene when its done loading.
That way only the texture will increase the size of the apk file (there are various other things like scripts and shaders that may go into the apk, but its probably images or other stuff thats increasing the size of the apk).