Put side by side by side to a few dozen 1971D its a lot bolder letteringing, numbers, imprint of Lincoln on sides of the coin the obverse and the reverse literally twice the size i only see this in 1971S commonly but this is a Denver? I don't know. Im probably incorrect i have been before lol.
So, nothing from any resource that suggests it would be a DDO/DDR, or that such a combination for that year/mm even exists? Bold lettering can also simply be a sign of circulation. Do you use a 10x loupe when you look for errors?
I'll say this part publicly, for any people who stumble across this. Stay away from YouTube. The people there make sensational videos that make huge claims because they need viewers to get paid. The more sensational the item, the more they get paid for their videos. It's in their best interest to make coin collecting sound as easy and profitable as possible, to make sure you keep watching their videos trying to strike it rich. The members on CoinTalk, however, get no pay for the great advice they impart to others. I highly recommend you study BEFORE you try searching for errors. I've been collecting errors for a few years. I've found DDOs, capped die strikes, clips, off-centers, etc. I've yet to strike it rich from any coin I've found. Very few people make big bucks searching for errors.