Change blockquote style?

I'm running a number of WP pages with various different pro themes. I imagine the answer will be the same for all (or most) themes but I'm posting here for the sake of an example. I like this theme but I find the blockquote style quite plain and boring, and not sufficie3ntly distinguished from the main text. https://catchthemes.com/demo/adventurous/about/page-markup-and-formatting/ There are a number of styles I prefer: This one from the Simple Catch theme seems is a little different, but not overly so, but is much better at distinguishing the quote. https://catchthemes.com/demo/simplecatch/html-elements/ vertical line/s to side of quote as per High Responsive theme: https://catchthemes.com/demo/high-responsive/style-gude/ Quote symbol as per Adonis theme: https://catchthemes.com/demo/adonis/style-guide/ or the more subtle version with muted quote symbol colour and more flowing/compact text of the fabulous fluid theme: https://catchthemes.com/demo/fabulous-fluid/about/page-markup-and-formatting/ smaller quote symbol as per Decree theme: https://catchthemes.com/demo/decree/style-gude/ or slightly more subtle Gridalicious theme: https://catchthemes.com/demo/gridalicious/2013/01/11/markup-html-tags-and-formatting/ So my question is: How can I change this please, does it require custom CSS and if so should it be done in a child theme? If you could provide the relevant CSS required and instruct where to put it that would be awesome ! Thank you.