How to open mat-menu programmatically?

You need to get hold of MatMenuTrigger instance from [matMenuTriggerFor] element

#menuTrigger="matMenuTrigger"  [matMenuTriggerFor]="menu"

where

• #menuTrigger is the template reference variable

• matMenuTrigger is exportAs property of MatMenuTrigger metadata

and then simply call

(click)="menuTrigger.openMenu()"

Stackblitz example

Read more about template reference variable here

• What is #auto attribute here and why it is required