silver tongued
C1 Advanced Oxford
describes someone who speaks in a clever and smooth way to persuade people. You use this when someone is very good at talking their way out of trouble or into a deal.
possessing a marked ability to speak eloquently and persuasively, often implying a degree of cunning or manipulative intent. Adjective, typically compound.
The silver-tongued salesman quickly convinces the crowd to buy his goods.
A silver-tongued lawyer managed to sway the jury despite the lack of physical evidence presented by the prosecution.
The diplomat was so silver-tongued that even his fiercest critics found themselves nodding in agreement by the time he reached his concluding remarks during the summit.