Where to find classic site collections on new Microsoft 365 admin center?

On home page of Microsoft 365 Admin Center click on "...Show all" from the left navigation(as shown in the below image)

Click on the Resources from the left navigation.

You will find "Sites" under "Resources", click on the "Sites" and you will get all the classic site collections you have created.

Check the below video tutorial for the same and please do like and subscribe my YouTube channel.