Does the magic keyboard work on iPad seventh generation?

No, iPad Pro only.

The Smart Keyboard works on an iPad seventh gen iPad

Absolutely NOT.

That keyboard is reserved for the 2018/2020 iPad Pro models ONLY.

Sorry.

Here is a good keyboard/trackpad combo case for the iPad 7th gen here.

https://www.logitech.com/en-us/product/combo-touch.html?crid=1762