How Do I Contact Expedia's Customer Service Number Official?

They have a live chat/virtual agent on their website; click "Help" button on bottom right of this page. Might be a good place to start.

https://www.expedia.com/helpcenter/

Otherwise I believe the number is (866) 310-5768, and I seriously doubt there's ANY way to circumvent being put on hold. My guess is that virtual agent/live chat will get you to someone more quickly but just guessing as we always book our flights directly with the airlines.

Unfortunately, you booked with an online travel agency and now you need service and there’s not set up to provide much in person service so you probably will have to wait on hold.

If you go on their website under Help, they have an entire article on how to change your ticket. maybe you could try that and you wouldn’t have to talk to anyone.

How to change your flight

When you change a flight you'll have to pay for any difference in airfare if the flight you’re changing to has a higher price than your original flight. Additionally, some airlines charge a change fee per person for a flight change.
Here’s how to get started:
Go to Trips.
Select Change Flight.
Search for new flights and book the one that works best! You’ll also see an estimate of your flight change cost, if applicable

https://www.expedia.com/helpcenter/?pwaDialog=article-dialog&product=Flight&productId=flight&articleId=16506

BBB shows a phone # 800-319-4834 (https://www.bbb.org/us/wa/bellevue/profile/online-travel-agency/expediacom-0654-90004878) and an average of 6 complaints per day

To add: the phone number I included above was from Christopher Elliot's website. He's a well-known advocate for customers facing issues with companies they do business with.
https://www.elliott.org/company-contacts/expedia-customer-service-contacts/