How do you make your Sim a mermaid without meeting one?

To make your Sim a mermaid without meeting one in "The Sims 4," you can use the cheat console. First, enable cheats by pressing Ctrl + Shift + C, then type in "testingcheats true" and hit Enter. Next, enter the command "traits.equip_trait trait_Oceanic" to instantly transform your Sim into a mermaid. Alternatively, you can also use the "Mermaid" potion if you have access to it through the "Island Living" expansion pack.