That is what their Masters tell them, and most RCs just say, "Oh, OK, our professionals say it's there, so it must be."
Again, their Masters do not deign to inform the peeons of where the distinctive RCC teachings are found, nor how they were derived. And, sola ecclesiasts that they are, the "apologists" are left scrambling through the Cloaca Maxima, trying to find any pieces that might – if squinted at imaginatively enough – be construed to explain how those teachings are really, truly, sorta, kinda, in the Bible.
Were they honest, they would say, "Rome said it, and I put my unquestioning faith in Rome. End of discussion."