Battery Life

Generally, there is no benefit to be gained by unnecessarily force-closing Apps. Allowing iOS/iPadOS to automatically manage Apps is more power efficient than manually closing Apps that are not being used.

Apps that were previously opened may be in an inactive state. Apps that you can see in the App Switcher may be active running as a foreground process, active as a background process, or inactive consuming almost system resources. When you resume an App from its inactive state, it will open from the saved-state and begin running almost instantly.

Fully closing an App both closes the App and removes the previously saved state. When relaunching an App for which there is no saved state, the App has to be completely reloaded and reinitialised - which takes longer and consumes more power. Fully closing and relaunching an App uses more power than simply resuming from a previously saved-state.

Resuming an Apps from an inactive/saved state is considerably more power and processor efficient than fully closing and launching afresh. As such, no, you should not need to fully close an App unless it has malfunctioned.