Having covid around helped them push mass mail-in voting which was essential to the steal. It halted the economy which was a strong point in Trump's campaign messaging. It gave them a weapon to batter Trump with in the media.

Moreover, it wasn't entirely about the election. It was also about the communist infiltration into the US (and around the world). Covid allowed them to torch our first amendment. To destroy small businesses all across the country. It allowed them to release criminals from prison. It allowed masked BLM and Antifa riots to rage for months on end (read: color revolution, and communist social justice riot tactics). It allowed them to break the American psyche and attempt to normalize this idea that individual freedom is less important than the safety of the group (you want to go back to normal? But you'll kill grandma!)

Many things at play.