Overriding Angular Material Size and Styling of md-dialog-container

From the official documentation:

Styling overlay components

Overlay-based components have a panelClass
property (or similar) that can be used to target the overlay pane.

You can override the default dialog container styles by adding a css class in your global styles.css. For example:

.custom-dialog-container .mat-dialog-container {
    /* add your styles */
}

After that, you’ll need to providies you css class as a panelClass parameter to your dialog:

this.dialog.open(MyDialogComponent, { panelClass: 'custom-dialog-container' })

Read this official documentation for more information.