two things: 1) if you didn’t submit your paper through an online plagiarism checker like turnitin.com then honestly there’s a 99% chance you’ll be ok, 2) if they do find out, first time offenders usually do not immediately get kicked out of school, rather they’ll probably give you a warning or reduce your grade in that class.
if you already know your college’s plagiarism policy is super strict and you’re still worried, another possibility is withdrawing from the course.
in the future, it is always better to contact your professor and ask for an extension or turn it in late than to plagiarize.
Anon, it also really depends on how much the paper sounds like your usual verbal and written communication with the instructor. If it sounds “off”, they probably will Google whatever sounds “off.”
I say this as someone who student-taught 12th graders and caught at least half of the students spread across five class periods plagiarizing because they 1) used words I was pretty sure they didn’t know and 2) used phrases that didn’t sound like the way they wrote other things or the way they talked.
But they didn’t use actual essays written by someone else; they copied directly–and in a few cases 100%–from website articles or Wikipedia, which made them a lot easier to spot than if they’d actually turned in a paper with citations in it.
As in the above advice, do ask for an extension in the future (I know asking things like that can be hard) and maybe talk with your instructor if you’re having trouble coming up with directions for the assignment.