I do not think that Trump was claiming that Pence had the right to overturn the 2020 election on January 6, 2021. Trump was claiming that the VP had the right to delay the proceeding in order to look into serious irregularities in the results.
The questionable results were a "show stopper."
"Overturn" is the wrong word. Restore the rightful winner is a more accurate description.
"What they are saying, is that Mike Pence did have the right to change the outcome, and they now want to take that right away. Unfortunately, he didn’t exercise that power, he could have overturned the Election!" (End quote)
President Trump sure knows how to expose GOPe jerks!!! He has Mike doing so much twisting and turning, the poor mans Skivvies are In a wad.