Yes, it is possible to change the position and size of the logo, but since you are wanting it to the left of the site title, I would suggest putting it into site title a and adding whatever left padding is necessary for the desired alignment. This would be the basic CSS. You would replace URL_OF_IMAGE between the quote marks with the URL of the image you upload to your media library and then adjust the padding as needed.
.site-title a {
background: url('URL_OF_IMAGE') no-repeat scroll left top / contain transparent;
padding-left: 50px;
}
The padding I included is just a placeholder.
If you have not yet done so, I would suggest creating a child theme so that any customizations you make will not be overwritten by a future theme update. Alternately you can use the Edit CSS function in the Jetpack plugin, or use one of the other Custom CSS plugins that will keep CSS changes from being overwritten.
Child Themes
Child Theme creation plugins
Jetpack plugin
Custom CSS plugins