This petition is similar to a petition from 2012 that asked to make all federal election days national holidays. You declined, noting that only Congress can create a permanent national holiday.
This is true, but: every president has the power to declare a one-time federal holiday by executive order. George W. Bush declared a national holiday on June 11, 2004 in memory of Ronald Reagan. While it would be great if Congress were to declare every election day a national holiday, it's certainly within the powers of the presidency to declare one election day a national holiday.
This is one of the most consequential elections in a generation. Declaring a one-time national holiday for this year’s election would give every American a greater chance to cast their vote and have their voice heard.