This one has a bit of history or explanation on Advent…then some suggested readings:
https://www.crosswalk.com/special-coverage/christmas-and-advent/what-are-advent-readings.html
Here’s another from Focus on the Family
https://www.focusonthefamily.com/magazine/advent-calendar
Here is a link to a number of Advent Reading Plans from YouVersion Bible
https://www.bible.com/search/plans?q=advent