Support for the OnePlus 5 has now been added to the SkipSoft Unified Android Toolkit.
The device has only just been released so there is no custom recovery or firmware images available yet. This means no root but all basic functions should work fine and as soon as anything is released the device module will be updated.
XDA Support forum: OnePlus 5.
To add support for the new devices you can either download the Toolkit v1.6.4 from *HERE* or you can run ToolkitClean.exe (assuming you have already installed the Toolkit) and select option 62 to update the Toolkit.exe file to the latest version.
If anyone uses the OnePlus 5 device module please give feedback in the forum as to button combinations to get to fastboot mode and on the bootloader unlock option to make sure it works as expected.