I use webp lossy for certain things and webp for others, the main way I control overall size is by adjusting max texture size. Remember that in texture profiles you want to put the most specific first in the list and most generic last in the list, which means you’ll possibly want to edit it directly in a text editor to fix the order.
PVRTC / ETC lossy formats specific to iOS (PVRTC)/Android(ETC), you don’t select webp lossy for them you select webp.
Check the list of the specific formats here for your needs.
When doing release builds you may want to use best compression instead of fast.
You’ll want to experiment with compression too. I recommend making a minimal project with assets you want to test and deploying that to the device to test how they look instead of doing your whole project over and over again since that can take ages.
Certain key assets / art I do not compress and also allow to have 1:1 atlas sizes since their clarity is important to the overall presentation of the game.
You can target both Android and iOS (plus other platforms) in the same texture profile file.
Here is an important related thread