Ok, Pradhana. This is going to be around about solution to your question, but the first thing that I believe that you would need to do is create a child theme. Go over to WordPress.org and do a little studying on how to create a child theme.
Then you’ll have to add a javascript file that is referenced from the functions.php file in the child theme. Once you get to this point, then you can start experimenting with Jquery to adjust the height of your logo. I would do a specific search on using Jquery to adjust the height of your logo.
I just googled “jquery to resize header logo on scroll down.” and got a nice list of options. Those jquery solutions is would go in the Javascript file that you add to your child theme. This should get you off into the right direction. Good luck!