Similar to what most people here are saying, if your phone is flagship-grade from the last couple of years, the glass it comes with will be stronger, if not as strong as any tempered glass layer you can buy.
Additionally, I refrain from using tempered glass add-ons --- assuming I drop my phone and damage the screen, I don't want the cracked tempered glass further damaging the phone glass beneath. If you really want, a softer film-type protector should suffice for preventing scratches directly on your phone glass.
To protect your phone glass, it's the phone casing that matters more. Choose a casing that has mildly raised sides around the display. If and when you drop your phone, especially face-down, the raised sides are what prevent the glass from hitting the ground.
I handle several dozens of phones every year for phone reviews and have broken a grand total of zero phones in the last 10 years. Dropped countless times though


