When choosing your A Levels, choose subjects you're extremely interested in otherwise the next two years will just drag. (Just saying though, sociology is fantastic! Was my favourite subject!). If you feel that you want to do 4 A Levels too, then do it. but trust me, you will have SO MUCH demand on you from just three A Levels. If you're wanting to boost your Ucas points, see if you can do an extended project. Universities love it when you can talk about an EPQ because it gives you so many transferable skills, like time management, having the ability to prioritise, detail orientation, etc. Also, the majority of universities only take points from three A Levels so the extra stress may not be worth it.
BUT a fourth A Level could give you an extra specialism, depending on what you wanna do long term.
Hope this helps!☺️