My mom had some cranberry juice that says best if used in 2018, and was wondering if it will do anything very bad to me, since it was sealed by a reputable manufacturer for this long, and never opened.
Best used is a date after which the manufacturer says quality will likely be reduced, not a spoilage date. Most items are safe after that date though some jurisdictions restrict selling after that date, but not using. That said, you are two years beyond that date. At two years, if in need and seals look good, no container damage, no discoloration, no gases, no off smells, no other signs of concern, then maybe it would be worth a risk. Your item does not fit that criteria in my opinion. The odds of it being bad are actually low, buy what need to you have to run that risk at all?