I prefer to say He /she died, though I understand that some people find “passed away” gentler. I do not like “passed”.
I have always been matter of fact about death, perhaps because I took the phone call about my Nan’s death when I was quite young, and her sister did not want to say anything ambiguous. She hop neded to be clear so I could tell Mum. I also took a couple of other calls about deaths of people who were important to us. All when I was about 10-12.
Now my sister is beginning to forget that our parents are dead and sometimes I have to remind her gently. I say “ Dad died”. Maybe the time will come when I don’t tell her any more, if she gets too upset, and just leave her in her own world. I don’t know.