The Apple Watch has not had a charge included for awhile, not just Series 7.
Apple get fined in some countries for including a charger. Apple gets fined in some countries for not including a charger. Apple cannot win.
Apple also gets a lot of pressure from Green Groups about e-waste, because many people have a dozen charging bricks in their homes as it is.
A while ago, Apple decided to stop contributing to e-waste and does not include charging bricks with iPhones and Apple Watches.
The unfortunate thing about that is, the charging cables are all USB-C, and the dozen charging bricks in people's homes are all USB-A.
Anyway, you can get any 3rd party USB-C charging brick you like or one from Apple. If you get a 20watt brick, it will do fast Apple Watch charging. You can also use any USB-C port on a personal computer. You can use your iPhone charging brick (assuming you got a recent iPhone). You can use your Macbook USB-C charging brick.
If you have an older Apple Watch, you can use the charging puck from that Apple Watch on your Series 7. It will not do fast charging, but it will charge the Series 7 the same as it did your older Apple Watch.