Some teas like boiling water… some teas like cooler water. Most green teas and oolongs work best with water in the 180 - 185 degree range. Yes, you can use boiling water… no, they won’t taste as good.
I’ve been mostly drinking darjeelings and ceylons for a long time and want to go through some of the greens and oolongs I have sitting around.
It’s easy just to boil water and let it cool for a while, but with the tea kettle I usually use it takes about 20 minutes to cool to the correct temperature! So I’ve timed it now and am recording it… it takes roughly 10 minutes on high heat to get the water in the kettle to 185 degrees. Very easy to remember.