Even if you're wary about rooting your Android phone and installing a custom Read Only Memory (ROM), you can still try out some features and settings that aren't turned on by default.
Every Android phone comes equipped with the ability to enable Developer options, which lets you test some features and access parts of the phone that are usually locked away. As you might expect, Developer options are cleverly hidden away by default, but it's easy to enable if you know where to look.

Find your Android Build number
Before you can enable Developer options on your Android phone or tablet, you'll first need to find your phone's build number. On most phones, you can simply type build number into the search field, but here's how to find it on a few popular devices:
https://www.technohepsco.com/2019/02/you-need-to-know-how-to-use-developer.html

What is it use for? That's what we want to know.

just tap build number 7 times

egbeocha:
What is it use for? That's what we want to know.

if your battery life does not last, you can use it to adjust some of the developer's settings to favor your battery life

pat077:
what else

after the seventh time, your developer's option is enabled. return to your settings and you will find it highlighted, ready to be used by you to effect changes according to your wish
https://www.technohepsco.com/2019/02/you-need-to-know-how-to-use-developer.html

What kind of changes

Developers option have always been available on Android devices from inception from Tecno n3 to Camon 11. I don't know what is so special about it.