I’m trying to build a Triton sorcerer and only get Draconian bloodline and giant soul and my options on the sorcerer origin drop down. Storm sorcery seems like the most consistent origin. Any suggestions?

is there something I need to purchase to have access in my character sheet?

 Do you own the Sword Coast Adventurers Guide?   That's the sourcebook that it comes from.

You need to purchase the Sword Coast Adventurer's Guide to have access to Storm Sorcerer.

Found it. It was a subclass in xanathars