Hi
it is good that you are being proactive but 13 is quite young to be in charge of other people's children. You won't find any business like a nursery that would employ you at that age. Their insurance wouldn't cover it and the DBS check wouldn't be possible.
As a mother I would not have employed a 13 yo babysitter.
I would look to how you can improve your chances when you are a bit older - do you have any sort of certificate in first aid for example?
At 13, once the lockdown is over, your options are more likely to be paper round, leaflet delivery or washing your neighbours cars.