How to configure Linux to automatically turn on at a specified time

What is the real time clock in Linux? Most computers have one or more hardware clocks which record the current "wall clock" time. These are called "Real Time Clocks" (RTCs). One of these usually has battery backup power so that it tracks the time even while the computer is turned off. RTCs often provide alarms and other interrupts.
Instead, the system clock reports the seconds and microseconds from the starting point, which is defined as POSIX Epoch: 1970-01-01 00:00:00 +0000 (UTC).
-- Real Time (RTC - Real-Time Clock) --
1 - Refers to the actual time of day, as set by the hardware clock on the system's motherboard.
2 - Typically, this clock is powered by a battery (e.g., CMOS battery) and is not connected to the internet.
3 - The real-time clock is used to keep track of the current date and time, even when the system is powered off or in standby mode.
4 - The real-time clock is usually set using a hardware button or by setting it manually through a BIOS setup.
-- System Time (System Clock) --
1 - Refers to the time kept by the operating system (Linux) itself. 2 - This clock is used to keep track of the system's internal operations, such as scheduling tasks, timing events, and measuring elapsed time.
3 - The system clock is typically synchronized with an external time source, such as a Network Time Protocol (NTP) server or a hardware clock (e.g., the real-time clock).
4 - The system clock can be set manually using commands like date or timedatectl.