If you want to get out and see some nature, head to Sai Kung town, take the bus up to Pak Tam Ao, and hike out to one of the beaches. Should definitely be warm enough to take a dip in the water so bring a towel and stuff if you want. I would almost only recommend getting HK style fried noodles from a small village like the sort you pass through on this hike. Much better than the salty MSG bombs you generally got throughout the city. This will take most of the day, though.
Suggestion 4 in this article has more concrete directions:
https://www.sassyhongkong.com/fitness-outdoors-best-beach-swimming-hikes-trails/
Yokozuna Ramen in Yau Ma Tei is good but probably not the best in the city or really a destination in itself, but has a special spot in my heart.
I checked out the Giant Buddha last time I was there and it was exactly what its namesake advertises.