The Royal has thankfully been unaffected by the current fires ravaging much of the East Coast and is only being closed to non residents when the weather conditions are severe.
If you are planning a walk check the parks website to ensure that the trails are open.
https://www.nationalparks.nsw.gov.au/visit-a-park/parks/royal-national-park
Also be advised that Bus Fleet has launched a new service within the park connecting many trail heads with public transport options. This allows you to access popular sites such as Wattamolla and Garie when the carparks are full or walk from Bundeena to Wattamolla and then pick up the bus to exit the park. Check this link for details:
Park Connections – Royal National Park Transport and Activity options