[oh, what a nice gesture. Cao Pi also appreciates that straightforward demeanor, facing him like that]

To some it would be Lord Cao Pi, but it's difficult to insinuate that on people over whom I do not rule. My style name is Zihuan...

[he wrestles with it for a moment and then decides] ...Cao Pi will do, but if you wish, you have my permission for 'Lord Zihuan.'

[it leaves literally everything about the proper use of style names completely unexplained, but since Javert asked, that's a succinct answer.]

Do you prefer your title or a more familiar name?