How to get dinosaurs in Sandbox?

Hello everyone! Wishing you all are doing great!

I'd like to adress a concern of why I do not have any dinosaurs in Sandbox? Does it have to do with setting?

I already finished everything in Campaign, besides California. Does this mean I unlocked dinosaurs?

How do you get large carnivores for Sandbox and other modes? If I am not mistaken, examples of large carnivores are T-Rex and Spinosaurus?