If you don't need the phone to be on all day, why have it on? Some Android customization layers even allow you schedule a time when the mobile is switched on and off automatically, without your intervention.
It must be emphasized that it is not a native option, but is one of those additives that manufacturers add in their layers. You have it, therefore, on Huawei, Xiaomi and OPPO / Realme mobiles with EMUI, MIUI and ColorOS respectively. We will also see what you can do with Samsung mobiles and other brands.
Huawei phones with EMUI
Huawei mobiles include the possibility of programming the system on and off for several versions of EMUI. To configure it, you must go to settings> Accessibility features > Scheduled on / off.
Turn on the main switch and then you can choose what time do you want the mobile to turn on and what time do you want it to go out. You can customize which days of the week you want the schedule to be repeated (daily, daily or custom days).
Xiaomi phones with MIUI
Xiaomi phones with MIUI have a similar option. This time you must go to the settings of Battery and performance and touch on Schedule on / off. In this case you can choose separately if you want to activate the automatic on and off, as well as what time and if you want it to repeat.
OPPO / Realme phones with Color OS
On ColorOS mobiles, the way to program the mobile to turn on and off at a certain time implies that you open the Settings and enter Additional configuration. Then touch Auto on / off and activate the corresponding switch to choose what time you want the mobile to turn on and off.
Samsung mobiles do not include at the moment the option to turn them on or off at a certain time, but what you can do is schedule them to restart. In this case the option is presented more as a way to "refresh" the performance of the mobile.
As a performance option, it is within Device maintenance, in the advanced options. Activate then Automatic restart and you can choose what time you want it to happen (although it will only be fulfilled if the screen is off, the phone is not being used, the battery is more than 30% and the SIM is not protected by a PIN).
Other mobiles (with root)
If your mobile does not have the factory option, there is no way that you can program it to turn on at a certain time. What you can do with applications is schedule it to turn off at a certain time, although you will need the mobile to have root access.
There are several applications on Google Play that allow you to do this, such as AutoOff, with which you can program to turn off when spend a certain time or at a specific time. In all cases, applications require root access, as it is logical to be able to turn off the phone is something that should not be within the reach of any application.