This is your responsibility to do your own research about how to keep your rabbit safe and healthy and how to provide the best care.
They should be provided with secure accomodation where they can feel safe, sleep, use a particular area as a toilet, and be confined to when unsupervised.
As rabbits designed to spend most of their day grazing on hay and other forage items, a rabbit stomach should NEVER be empty and generally won't survive for long should they go for more than 12hours without food.
Rabbits are very social animals and generally should not be left alone for a long time. Leaving your bun unsupervised for more than 24hours increase the risk your bun gets stressed and stops eating, gets GI Statis or gets sick.
Five common diseases that affect rabbits:
Gastrointestinal (GI) Statis
Dental disease
Uterine tumors
Head tilt
Respiratory tract infection
For young, healthy rabbits seeing a vet once a year for a routine checkup is generally recommended. This is also true if your bunny has been unwell or has an injury.