Looking to add underline when hovering over a link the body of a post? After trying a bunch of css variations this is the one that works. Go to Appearance/Customize/Custom CSS/JS and add this piece of css.
body.single-post .entry-content a:hover {
text-decoration: underline;
}
For pages including home page:.single-page-article a {text-decoration:underline;}
Set majority of site link colors in OceanWP Customizer/General Options/General Styling
example Elementor link customization in CSS/JS.h3.elementor-image-box-title a {text-decoration:none}
For underline links on your blog posts listing page and archives use this..blog-entry-summary a:link {text-decoration:underline}