If there is no official Android 7.0 update for your hardware, the only way to reach that version is by installing a Custom ROM like LineageOS.
Even with a verified ROM, you will lose some functionality compared to KitKat. android 442 update to 70 verified
: This power-saving feature, which began in Android 6.0, now works even when the device is in motion (e.g., in your pocket) to save battery. Customizable Quick Settings If there is no official Android 7
The short answer is The long answer involves custom ROMs, bootloaders, and a bit of tinkering. which began in Android 6.0
If you find a video on YouTube with 500 views promising the update, but no XDA thread exists— do not flash it . You will brick your device.