I only have 1 app downloaded is there a way to download my app to iCloud and play it from there on my ipad

For most apps (possibly excepting web-based apps), no.

Games are downloaded from the App Store, and generally not transferred directly among iPhone and iPad devices.

Once you have gotten a free app or paid for an app from the App Store, you can download it to any compatible iPhone or iPad.

The only apps that can run in iCloud are those online apps Apple provides directly with every iCloud. Apps from the App or MacOS store must be installed on an iOS, iPadOS or MacOS physical device in order to be executed.

Not from iCloud.