just got my new series 7...don't see a charge cube

Charge cube? You mean a power adaptor? Apple no longer ships a charging adaptor with Apple Watch. Apple's online store mentions this and suggests if possible you use an existing adaptor from your collection (many users have multiple spares). The online store says:

Compatibility

As part of our efforts to reduce our environmental impact, Apple Watch does not include a power adapter. Please use your existing Apple power adapter or add a new one before you check out.

If you don't have a suitable adaptor they can be ordered from the online Apple Store, or over the counter in most electronics outlets.

It doesn't come with a power adapter.

See the following from https://www.apple.com/shop/buy-watch/apple-watch?option.watch_cases=MKNQ3LL/A&option.watch_bands=ML7Y3AM/A&preSelect=false&product=Z0YQ&step=detail#

As part of our efforts to reach our environmental goals, Apple Watch does not include a power adapter. Please use your existing Apple power adapter or add a new one before you check out.