Use APKPure App
Get CPUSpeed old version APK for Android
Set CPUSpeed for some rooted android devices
CPUSpeed only works for rooted devices and it helps you to change CPU speed easily.
Please note that if you underclock your device, it might freeze or even shutdown in the worst case. If you overclock your device, it might become warm and battery will run out quickly.
This app might or might not work on your device. If it doesn't work, please try other apps.