Look into ortho-k contact lenses. My siblings all have terrible eyesight but mine is ok around -1.5 and I was the only one who used ortho-k contacts.
But on the other hand, the UK NHS guidance https://www.nhs.uk/conditions/short-sightedness/ says that multifocals may help slow the development, while "Some opticians may advise wearing a special lens overnight (orthokeratology). This can help you see better without glasses or contact lenses" (so the UK guidance does not list ortho-k in the list of things that can slow development, only that opticians may advice using it)