Change font size in a specific page AND specific title of a text widget


We would like to have different font size for this specific page on our website :
We have many text widgets on this page, is there a way to have a different font size for each different text widget? Where do we put the CSS code?

Also, on this page :
We would like to change the font type and size of a particular widget title. It’s the one with the subscription form to our newsletter. The title is “Abonnez-vous à notre infolettre”. Where do we have to put the CSS code in order to achieve that?

Thank you so much!

Hello there

First of all, css code can be placed in appearance > customize > additional css
Wordpress page editor has the option to select text and change color, size or font weight, so no css is needed for this

Thank you for your response.

It is our first website, and we’re obviously still learning. We still don’t know how to find this option on our page editor. Can you tell us step by step where do we find that option for every specific page and post?