Opinion articles aren’t factual journalism but rather the author stating their opinion.
Reason for that being if they’re making a claim they cannot back wholeheartedly, they will write an op-ed instead of an article.
How old are you? This is very basic.
What you're saying is really absurd.
A fact is a fact regardless of whether or not it is contained within the context of an opinion piece. And it's perfectly normal for a journalistic outlet to contain opinion pieces and it's perfectly normal for the writers of opinion pieces to include facts to bolster their arguments.
If I'm writing an opinion essay or a book against the death penalty (of course I'm for it but just being hypothetical), it would make sense that I include some fact like "between 2010 to 2020, the state of Louisiana executed three men who were later proved to have been innocent".
And if you come along and say that my piece is an opinion piece and therefore my "fact" (which I just made up btw- it's just an example) is invalid- that would be completely absurd. It's either true or it's not but that's determined by whether what I'm saying is based on accurate data, not whether or not the fact is mentioned in the context of an opinion piece.
If I read a book called "The Case Against Abortion," just because the book is polemical doesn't mean whatever facts are mentioned are necessarily true or untrue.