How to scale down textures for android devices?

I am new to this. I am very confused about how the downscaling is done for android. Say If I 4K textured model, how can I have it 2K in android devices or maybe have 2K in the PC build?

I believe LOD is for polycount. Just an another question , can I specify which LOD to be considered for packaging?

Some references will help a lot.

Please help reg this

There is also a LOD for the texture, take a look in the texture editor.

With Android, you might want to make separate versions of the textures, otherwise, even though you are still using the texture at lower res in game, the full texture is still sitting in memory.

Thank you. That helps.