Not an actual soft play place, but the local leisure centre would put a load of mats down and foam squares / triangles to jump over. Seems quite dangerous looking back actually, they all used to slip around leaving you open to falling onto a bare badminton court floor. A few random carpet shops used to have a ball pit and slide too, they always smelled funny. No actual soft play warehouses, I only became aware of those when I had kids, and even then only went on a weekday as toddlers. Having seen a birthday party in a big one on a rainy weekend - fucking fuck that.