Can you really die from putting a plastic bag over your head?

I don't know, try it.

Are you trying to harm yourself? Should I report you?

Very painfully, yes.

yes i believe you can

Yes, because it can restrict breathing.
That is why people with unattractive lovers want them to put a paper bag over their heads instead.

Yes, it's even recommended by that assisted suicide society. Do NOT experiment.

Can you

depends how you do it.
you can die from too much water🤷‍♀️
you can die crossing the road.

More the question is, Why would youwant to put a plastic bag over your head?