In reply to Alex.

It will depend on your theme. Most likely, you'll need to adjust the top or bottom margin for paragraphs. Not knowing what your design is like, I can only give you some general advice. Try one of the following two CSS adjustments. It should work but may need some adjustment.

p {
margin-top: 2rem;
}

Or:

p {
margin-bottom: 2rem;
}

If it doesn't change anything at all, you'll need to ask your theme author or hop over to the WordPress.org support forums.