You need to have a job to use the promotion cheat for Sims 4 careers.
This guide will let you know how to promote the Sim 4 career with the help of cheats.

Step 1
You have to press “Ctrl+Shift+C” at the same time to open the cheat bar!
Step 2
To level up in career, you will need to type in “careers.promote >name of career<”.
Before you do this, type in “testingcheats true”.

Step 3
You have to do this more times if you want to level up more and reach the highest level.

Step 4
After that, go to the Sims 4 VIP website if you need more cheats.

Type in now “careers.demote> name of career<” to level down on your career!