Using Always on Display (AOD) on your AMOLED screen phone, including Oneplus devices, should not cause any significant damage to the screen. The AOD feature is designed by manufacturers to be safe for regular use without causing any issues. However, it's worth noting that using AOD may slightly reduce the overall lifespan of the screen due to the continuous display of pixels, albeit in a reduced brightness mode. Nonetheless, the impact is usually minimal and should not be a cause for concern.