They didn't plan. They got marching orders from Trump in his speech that day.
They have to send the results back to the swing states to be redone. Trump claimed that all the swing states wanted them back for a redo. They just needed to convince(intimidate/threaten) Mike Pence to do the "right thing" and send them back, then he would win the election and they would be the happiest people... and if they didn't the country would be destroyed...
Who knows what Trumps plan was if Mike Pence did the "right thing" and sent the results back. Unleash more mob terror and intimidation, in those states until he gets the results he wants, then sends it back with the result he wants and he is president all
fair and square.
While that seems crazy to us, Trump and his cult don't run on human values. If you can believe that you could Intimidate Mike Pence into returning the results, then it isn't much of a stretch to think that you might do more intimidation, to get the results you want with the same tactics.