With macOS Monterey, Apple included Low Power Mode. Just like on iPhone, Low Power Mode conserves power by reducing the screen brightness and the processor clock speed. However, unlike iPhone, you cannot pick a specific battery percentage for Low Power Mode to automatically kick in.
How to enable Low Power Mode
Open System Preferences
On the lefthand menu, Click Battery
Check Low Power Mode on the bottom of the checklist
To use Low Power Mode while your Mac is charging, on the left menu, click Power Adapter
Check Lower Power Mode on the bottom of the checklist