Asus revealed the Zenfone 7 and 7 Pro last month, following months of rumors and speculation. If you don't plan on sticking with the stock ROM, Asus has now released the bootloader unlock tool for both phones, as well as kernel source code packages for developers to try out.
The support pages for the Zenfone 7 and 7 Pro have now been updated to include download links for the bootloader unlock tool, which is less than 1MB. However, the program is accompanied by a warning that your warranty might be voided:
Before you download, install, and use the Unlock Device App (“Service”), you understand that you need to take all risks in terms of quality and performance of the Service, including but not limited to: once you trigger the Service, you’re not able to recover your ASUS products to the original status at the time of manufacturing (“Original Product”) anymore. [...] In addition, the software and hardware problems of your ASUS product caused by using the Service may not apply to your ASUS Warranty Information, please read ASUS Warranty Information of your ASUS product carefully on ASUS official website.
Asus has also released kernel source packages for both phones, coming in at 508 MB for each model. The code allows developers to more easily create custom ROMs and recoveries for the Zenfone 7 series, so expect a rush of third-party firmware soon. While you're waiting, why not read our new Zenfone 7 Pro review?