Android is not a bad system. And you don't need to worry about what's running. Android will close apps as needed automatically. Android is very good t handling running processes and memory for you.
That doesn't mean everything is always perfect. Sometimes poorly coded apps cause trouble. Android is not perfect either. But the answer is not to fight the OS and try to force it to run in a way it was not designed to. Better to find the cause of trouble and fix it. To do this install System Panel. It's aan excellent tool that will tell you what is really going on with CPU load, RAM memory, running and inactive processes etc.
https://forums.androidcentral.com/e...details?id=nextapp.systempanel&token=H2OD4Isq
System Panel makes basic trouble shooting of a sluggish device simple. Look at the opening screen, 1st one when the app opens. It gives the basic information you need. With the phone at idle (apps can be open, but nothing such as an active phone call or file transfer) check CPU and RAM memory usage (pie charts upper left corner).
Normally, CPU should be less than 5-10%. CPU clock speed (top horizontal bar) varies but should be something less than max. RAM usage should be about 70-80%, unless you have recently rebooted and not yet opened apps to load RAM. You want to check these values after a fresh reboot, after some normal usage and when the phone has slowed.
If CPU is high, look at the app list on the same screen. Check the CPU usage for each app (small vertical bar on left edge, next to app icons) for offenders.
If RAM usage is too high, again on the opening screen look in the Active Applications list. Check for a running app you have not used recently. It may not have closed or cached properly and is holding RAM. If nothing seems unusual in the Active Applications, scroll down to Inactive (Cached) Applications. It may be harder to determine what belongs in this list and what doesn't, but if something looks iffy, particularly if it shows holding a lot of RAM, you can try long-pressing on it and select 'End Task'. If you select a required system process, no worry, it will just restart. If RAM usage returns to normal and/or the phone feels faster, that could be the offender.
Troubleshooting beyond this gets more complicated, but what is outlined above will find most problems causing sluggish performance