No NASA or trust in authority required, a basic astronomy telescope allows observation of Saturn and its rings.
From an 82 inch telescope:
What a fantastic, incredible image.
Truly unbelievable.
Look at all the stars.
Have you really ever looked through a telescope and seen Saturn? I have, not as big a telescope as that one but I have clearly seen the rings.
I went to a "Star Party" at Mc Donald Observatory.
They had some small telescopes aimed at various objects.
One of them was aimed at Saturn and that was what I saw.
Incidentally you only saw it in black and white on this telescope since your eyes can not see colors in dim light.
Most of the colored pictures of planets, nebulae, etc. were made by long time exposures to bring out the colors you see on those photographs.
Once again I would recommend a visit to an observatory and a "Star Party" for flat earthers.
I believe they would find it an eye opener. (If you will pardon the pun. LOL.)
Of course they would probably say the image of Saturn and its rings was just "a pretty picture drawn by NASA and painted on the telescope to make you think you are seeing Saturn."