How do I update iOS on my iPhone 11 ?

Assuming you have a compatible device, see: Update your iPhone, iPad, or iPod touch - Apple Support

And: If your iPhone, iPad, or iPod touch won't update - Apple Support If the above Apple articles do not help, please post back with relevant information. 

Update iOS in 11 pro max

geet274 wrote:

Update iOS in 11 pro max

You have to update your own iPhone. We cannot do it for you.

Read the answer that was already provided.