My computer is shutting off when I load the Sims 4.

Your laptop will only stay on long enough for you to login to what? Windows? Origin? Your Sims neighborhood?

It isn't possible for The Sims to shutdown windows or deactivate your hardware therefore it's either overheating or your power supply is failing. Try installing SpeedFan and monitoring your hardware temperatures while The Sims is running in windowed mode so you can see the SpeedFan display. Anything over 190 degrees Fahrenheit is critical and if the temperatures are safe then the problem is likely your battery and/or power supply.