If you don't have a Tire Repair Kit in your model 3, I highly recommend that you purchase one ASAP since there's no spare tire/run-flats. I went to a concert this weekend wish was over around 10:30 PM. When I made it to my car, the rear passenger tire was completely flat. I called Tesla Roadside assistance, and I was told that the company available to service my car did not have a loaner tire. I remembered that I purchased this tire repair kit https://www.amazon.com/dp/B0166BVK28?ref=ppx_pop_mob_ap_share from Amazon. I hooked it up to the car/tire to see if it would hold any air before I injected the sealant which it did. I thank God I was able to inflate the tie and make it home and the next day I inflated the tire and drove to Discount tire, and they removed the nail plugged the tire.
You can buy the tire repair kit from Tesla https://shop.tesla.com/us/en/product/vehicle-accessories/model-s_x_3-tir..., However, you'll be paying $57.00 more than the one I posted above.
FYI for tire repair at a 3rd party service center:
If you take your Tesla to a 3rd party service center, please, please, please make sure they have the jack pads. I would suggest that you buy one and keep in in your car because Discount tire didn't have them and tried to use the jack without one, luckily I was watching them and made them use the one I had. Here's a link to the one I pushed from Amazon https://www.amazon.com/dp/B07PDLYNDJ?ref=ppx_pop_mob_ap_share
Update 4/15/19 @ 4:17 CST
The tire plug kit is a better option over tire sealant kit. However, you still need to purchase a tire inflator.