If you don’t have either of the books recommended above, here are a couple of good sources on equanimity available online.
Shaila Catherine has a good description of equanimity and some suggestions on how to practice it that you can find here: Equanimity: Our Greatest Friend
The following article on equanimity by Gary Gach was written at the beginning of the COVID-19 pandemic in the Spring of 2020. However, it feels very relevant to our current situation as our hospitals are again in a state of crisis. You can find that article here: Practicing Equanimity in a State of Emergency
Insight Meditation of the Mid-Columbia