If you have an aptitude for picking up concepts rather quickly, then go for it -- but only if you feel as though you can devote ample time to all four subjects throughout the year (you may have to make sacrifices on your free time where appropriate).
Back when I did A-levels, I did 5, plus the EPQ, AEA, the STEP exams and BMO on the side. That was almost pushing my upper limit on being able to maintain mostly A*s across the board, but the exam season sure as hell wasn't fun. I became a social recluse for several months to be able to perform at the level I needed, and I do think it had a material impact on my mental health after the exams had finished. Was it worth it in the end? For the purposes of university, no. One big plus is that it's often a talking point on my CV (mostly along the lines of why the hell I bothered to do that many subjects), but that's about it. I don't think it gave me much of an advantage over other applicants who had 3 or 4 A-levels. And it's a pain in the ass to enter details about all these qualifications when I have to comply with background checks.
In my case it was a gamble which, despite getting good grades, didn't really pay off. I could have used my spare time doing something else (though it's not a given that I would have done so even if I did have the spare time).