Is there a cord to add RCA inputs to a TV without RCA inputs?

actually yes there is !!
vcr's used to do this all of the time.
you would plug in a video game with the yellow video cord and the video would be sent out the coax cable into the television.

if you try to find an 'adaptor' that does this, you will probaby look high and low without any results.
vcr's are being sold as used and abandoned all over the world still.
i just looked on ebay and there are over 20,000 items listed for 'vcr'
see if this is your first chance to grab an auction for super cheap?

since most people dont watch vhs tapes anymore, the only other reason to use 'em is for the video adaptor on the back.
other than that, i would say they are total worthless junk if you already have a dvd or bluray player.