Don't force yourself to do random extra-curriculars just for the sake of selective; coming from experience, its not enjoyable to do so much random extra-curriculars because you rarely have time to adjust and focus on recreation. Rather go to one or two extra-curriculars or committments aiming to achieve high and dedicate a good portion of time to that, for e.g scouts, aim to become a pack leader or gain X amount of badges. Its better showing to admission committees that you are able to manage time effectively through excelling in your extra-curriculars/commitments and school rather than you're in loads of clubs and organisations but you don't have anything noticeable than your participation. I suggest you research some clubs or organisations outside of school, at least 1 or 2, that pick up your attention and interest you to an extent you're willing to dedicate your time to it then choose it on the basis of your interest and self-development rather than solely for selective.
If doing extra-curriculars feels like a burden than something enjoyable, don't do it, simple. Why waste loads of time and energy on something just out of hopes to gain entry into some school. If you're **decently fit**, I suggest joining a soccer or cricket club because they don't drain as much time or energy (sometimes) to an extent that its noticeable, unless you're doing reps etc., because just playing every week for 4-5 hrs makes you way more active and energised which carries to your studies; from experience.
If you like music, try the guitar, there's many variants of it but just get an acoustic guitar. Its always satisfying after playing a riff, you feel so proud of yourself after learning chords etc. There should be smaller sizes if you worry about it being too heavy but it is definitely worth a try - I really enjoyed playing it a lot, you'll also notice your fingers toughen up a bit after a while which is pretty cool and there's so much more I won't spoil. Perhaps when the lockdowns lifted, try going to a music class and just ask to try out a guitar and play a basic chord if you want a feel.