How to split or float multiple apps, or have an app running in the background on Iphone?

I'm aware that there are many web browser splitters, but I need something that can have an app that's already open to keep running even after I press the home button.

Alternatively, it can be something that allows me to split screen or float the app so that the app is not considered 'paused' or shut down by the system.

Any help?

2020-08-13T01:22:35Z

Iphone 8, btw.

2017-04-11T00:37:33.809Z