Can you please share your website URL so we can check?
If you are using free theme, you can change the logo image height/width by
Go to Appearance -> Editor -> functions.php
at line no. 34 you will find the below code and change height and width
add_theme_support( 'custom-logo', array( 'height' => 100, 'width' => 100, 'flex-height' => true, ) );