How to resize the fonts in a sentence

May I know how can I resize the fonts?
In a sentence, example “I have a dog”, can I configure “I have a” and “dog” in different font size?

Please advise.

Use a <span> on the portions you need to be different, and then give them a class, and style them with css.

Something like:

.giant-dog-font {
font-size: 3em;

I have a <span class=“giant-dog-font”>dog</span>