Hi there, I was testing out functionality after adding eleven accuracy to my character.  I noted when trying to attack in app, using the with advantage option, the it only rolls two die.  
is there a way to automate eleven accuracy so that it rolls a 3rd die and selects the best result?

There is no way to automate it.

Just in case this is a conversation that people are still finding, using the beyond20 browser extension (i'm using google chrome), holding left shift when you click your attack roll rolls it at advantage, and holding right shift when you click your attack roll makes it roll with super advantage. Same for the respective Ctrl keys with disadvantage.

also, try right clicking, also provides the same