You need to go through all the other modes to unlock all the dinos and stuff there for sandbox. I think there are some lists out there where you can find what, maybe search for "unlock guide JWE2" that should bring it up and hopefully help a little. Or you go to nexus and download a 100% complete save from there if you don't wanna grind for everything yourself.
And to answer the other question: no, there's no such option because Frontier somehow though it would be a great idea not to include that vital option/feature for snadbox in their park manager game and then also went a head and put completely unneeded and stupid restrictions on the so called "challenge mode" in this game.
So in the end we don't have a single map or option in our park builder/manager game where we can actually build up our park from scratch and use everything there is as we grow and develop our parks. Which is really a shame and something a whole lot of players hope will be fixed asap.
