Logo can be changed from below code inside the header container.

<!-- Logo START -->
<a class="navbar-brand" href="index.html">
	<img class="navbar-brand-item" src="assets/images/logo.svg" alt="Logo">
</a>
<!-- Logo END -->

Logo height and padding:

By default logo height is 40px. To change logo height, You should change the value in $navbar-brand-height in _variables.scss file as per your need. You can also change sticky logo height, responsive logo height and logo padding to set header height from _variables.scss file as per your need. Please note that if you increase logo height, your header height will increase automatically. You don't need to change your header height manually.