Why would my Lexus 2013 RX 450h suddenly just not start and all the lights on the dash and outside started flashing and slowly drained the battery all the way and unable to start or even lock my car

It sounds like your main 12V battery is exhausted and either something was left on in the vehicle or the battery just needs to be replaced. Battery replacement is typically recommended every 3-5 years regardless of condition. A battery may show signs of life (lights come on etc.) but it may not have enough energy to cycle on the vital components in the vehicle and as you may try to start the vehicle the output will draw down below the systems minimum requirements creating many system operations functions. There is a chance that there may be other charging system issues (Alternator, power connections, poor ground supply) but if you haven't replaced that 9 year old battery yet I would recommend starting there.