When someone dies, do we say they expired or passed away?
Does the word expired give any more respect when used? Or less respect than passed away?
As others have pointed out, "passed away" is a euphemism.
Its use is not so much about respect for the dead, but about consideration for the bereaved. It suggests that the person has gone to heaven (or whatever other afterlife you care to imagine).
We also use "gone to a better place", and we wish that the deceased "rest in peace". We sometimes see "eternal sleep".
Hence we avoid reminding the bereaved of the blunt finality of death, and concentrate on an analogy with something more comforting.
"Expired" is a very blunt direct term for death, which emphasises its finality and gives no hint of a continuation in the afterlife.
Use the euphemisms in situations where you want to be sensitive to the feelings of people who loved the deceased.
"Pass away" does not convey any meaning other than "die", while "Expire", in my opinion equals "expiration of life" or "a person coming to an end" in this context.
With this perspective, "pass away" does not include any synonyms of "death", "die", "end of life" or "end". It is a euphemism.
In usage, you'd be inclined to avoid directly mentioning "death" or "end", to sound more respectful. This is where "pass away" as a euphemism, seems appropriate to be used with a sense of respect.
There is nothing wrong or less respectful in using either expire or pass away to denote the death of a person. The issue with expire is that it is archaic usage in most parts of the world and might possibly be misunderstood. However, the term is perfectly normal and continues to be used in this capacity in many parts of the British Commonwealth from Kenya to Bangladesh (or India which is where the OP is from).