It also doesn't hurt to be able to say "I already bought a GT. I'm curious about the Pure and would love to take it for a spin to see how it's different."
If you're not already a Lucid owner, they may be limiting test drives to reservation holders still. It's a pricey car. So that's somewhat understandable, given Lucid's limited staffing. I imagine that will lift eventually. But maybe not. I'm pretty sure many expensive cars still require some sort of deposit for a test drive.
Once you are an actual Lucid customer, you rightly will get more slack when making simple requests. The sales associate would be an idiot not to grant you a test drive. For all they know, you have a son, daughter, cousin, friend, whatever who you could easily convince to buy the car. You'd be doing their job for them.