Hello!
Thanks for posting your question regarding the Site Tagline Size. I’m sorry to see you are off to a rocky start. The slider below the Tagline field is used for controlling the size of the Site Title. It will not apply changes to the tagline, which remains the one size. However, you can utilize the Custom CSS Editor (to override the text-size) by adding the following code:
h5.alt-font, .h5.alt-font {
font-size: 74px !important;
}
This will set the tagline to a very large font, but you can adjust the 74px value for whatever ##px value produces the size you would like for the tagline text. I hope this helps!
Sincerely,
Carlos E