How/where do I type in extremely small font?

In print, you’d use small font sizes for copyright pages and the like—information that needs to be there but that isn’t particularly important for people to read easily. (It shouldn’t ever be set so small as to be illegible, however. If there’s too much to fit on one page legibly, request a rewrite.)

For web/screens you could use smallER font sizes for less important information, but never extremely small sizes, because you aren’t going to pay more to print (fontvilla small text generator) extra pages as you aren’t printing ANY pages, and it is already harder on the eyes to read on (backlit) screens than on paper. If you just can’t bear to have such information cluttering up your design, better to incorporate a link to a separate page.
AND
How/where do I type in the extremely small font?

Hi There,

Thanks for the mail.

The only option to modify the font size for the copyright and footer credits would be using custom CSS.

Kindly have a look at the following regarding the license details.

https://colorlib.com/wp/licence/

Hope this helps.

Cool Fancy Text also give you this option. You have to go for this.