When will be push Android 11 update in OnePlus 6.
Sometime between now and never
Please use the search before creating a new thread, there are similar threads already open and answered.
Oxygen os 11 is still under development for your device model by OnePlus. It will be released when it is ready.
There is no ETA.
Please read and use this thread for further discussion
All about OxygenOS – Nov 2020
by Gary C., 2020-11-16