Android 8.0 and later, normal app could not get the CPU information, so the tool always shows 0 for CPU utilization. I could not find workaround against OS designed changing.

***** If you cannot see the Task History List, please add "Usage access" right in Apps with usage access configuration manually.*****

Resource Monitor X21

Resource Monitor X21 has the trend graph to see the CPU utilization, memory usage, and battery information.

Also this tool can view the running task history list provided by android OS. On the activity, you can optimize the memory usage. The tool tries to kill the running tasks with using the task list from context menu.

Also you can long tap a task in the list that you want to show, then the tool tries to kill other tasks in the list and invoke the selected app.