The Sims 4 features many Traits beyond those found in Create-a-Sim. Traits often provide bonuses or penalties of some sort, and it may be desirable to remove them. Here is a list of all traits in The Sims 4 and the codes you need to equip them. Although you probably found this page there, my site does feature an extensive list of Cheats in The Sims 4 if you would like to learn more.
How to Cheat
In order to cheat traits, you must first bring up the console by pressing Control + Shift + C. Do it all in one fluid motion with your keyboard. Playstation and Xbox players can do this by pressing all four shoulder buttons simultaneously.
Create-a-Sim Personality and Bonus Traits
I would type traits.equip_trait bookworm to get the Bookworm Trait. Included in the list are the bonus traits you get for selecting a category. Children do not get bonus traits, so none exist for their aspirations.
Reward Store Traits
You can also cheat reward traits, exactly the same way. Equipping these will give you the bonuses just as if you had bought them with satisfaction points from the rewards store.
Aspiration Reward Traits
Sims gain reward traits from completing Aspirations, which tend to relate to that Aspiration's theme. For example Angling Ace gives Fisherman's Tranquility, soothing negative moods while your Sim is fishing. Since these are all tied to an Aspiration, I'm also listing the name of the aspiration next to it.
Parenthood Character Value Traits
The Sims 4 Parenthood includes a Character Values system, which either gives good or bad results in each of the categories of parenting. The following are the traits that you can only get if you raise a child or teen and instruct or neglect them. Sims made as adults don't have these traits.