Aukley 2-Pack Clear Glass
So far the reviews for OnePlus 5T protection isn't that great. Most screen protectors don't fully cover the screen, raise up, or have the halo effect around the edges.
A brand that has solid reviews, albeit only a few, is Aukley. What makes these protectors great is they have color-matched frames around the edges. That way you won't get the halo effect on the screen. OnePlus curves the glass just a tiny bit, which is why a lot of protection doesn't fit right.
So, try out the 2-pack of tempered and strengthened glass screen protectors from Aukley. You'll get two, in case the first installation goes wrong or ever breaks.