As in "there is no such thing as true or false, only opinion"?

That's completely unrelated. Obviously there exist objective facts, but outlets get to pick and chose which facts they report and which ones to hide under the rug. For example, its common for state news organizations to report enemy losses, but omit their own.

Some propaganda goes beyond selective disclosure of facts, like Al Jazeera uncritically reporting questionable claims as long as they're anti-Israeli, and failing to retract the ones that turn out to be false.

In a post truth society, certainly. If you can't verify it yourself it's all a leap of faith.

"Verifying it yourself" is often if not usually also a leap of faith, because how shall a single mind error check itself in a confirmably reliable manner, especially if it's received no specialized training in the domain?

It comes down to the relative stretch of the leap you take.

And to know that, you need (just for starters) a means of discovering what is True...so you are back to the problem I noted.

Luckily, all of this complexity can be wallpapered over by cultural conditioning, making the problem essentially vanish (depending on the frame of reference one is observing from, or if one even knows what that means).