How to transform text to lower case in ShopIsle

You can get rid of the auto capitalization of text for the most part in ShopIsle theme by adding following custom CSS in your child theme, or using a plugin, like Advanced CSS Editor:

.module-title, .features-title, .alt-features-title, .btn.btn-border-w, ul.products li.product h3, .wccm-td div, ul.products li.product h3, .wccm-td div, ul.products li.product h3, .wccm-td div, .copyright, .navbar-custom .nav li > a { 
text-transform: none;
 }

If you are using WP 4.7 or later then you could just add the code to Appearance->Customize->Additional CSS.