[Grace Themes]

Hi,

To resize / set width and height of your logo image

Go to Appearance -> Editor -> functions.php file

at line no. 39, you will get the below code

add_theme_support( 'custom-logo', array(
	'height'      => 80,
	'width'       => 150,
	'flex-height' => true,
) );	

Just change the height and width for your logo image.
Then you will need to remove logo and again set new logo image from Appearance -> Customize

Regards
Grace Themes