Hey there,
I hope you are well today and thank you for your question.
You can try achieving this by adding the following CSS code in the Custom CSS option of your theme on the below path.
Admin Area -> Appearance -> Customize -> Additional CSS
/*Increase font size and weight*/
.flex-caption .post-categories a, .flex-caption .read-more a{
font-size:1.4em;
font-weight:700;
}
In regards to increasing the number of slides, you can consult this thread here.
https://colorlibsupport.com/t/increasing-the-number-of-featured-posts-in-the-slider/
Best regards,
Support.