How To Increase Size

Do you mean the Category tabs?

Yes

Try adding the following CSS overrides in the wootabbed settings area:

.wtcpl_category_nav li a:link, .wtcpl_category_nav li a:visited, .wtcpl_category_nav li a:active {
    font-size: 18px !important;
}

.wtcpl_category_nav li {
    min-width: 190px !important;
}

You can change the values as needed.

Thanks

Thank you

You are most welcome!
When you have a moment please consider leaving the plugin a geat rating. I will appreciate that. You can do that from here:
https://www.ads-software.com/support/plugin/woo-tabbed-category-product-listing/reviews/#new-post

Thank you!

I gave a 5-star rating.
Can you also tell me how I can add a border around each separate category?