In "Planet Coaster 2", mechanics and cleaners are very important employees in the game and are basically indispensable. If you want to hire a mechanic, you can open the employee tab, select the mechanic and put it into your park.
How to hire a mechanic in Planet Coaster 2
Before you can start opening your rides, you'll need to hire some staff. Specifically, you'll need to hire a janitor to keep the park clean and a mechanic to perform maintenance and operation on the rides.
Open the Staff tab, select a cleaner and drop it into your park. Likewise, in order to hire a mechanic, you need to do the same thing. You can hire more workers as needed, but you only need to hire a janitor and a mechanic to complete your goals.