Hello @tompearse,

First of all thank you very much for using the pro version of the theme.

Now to increase the size of the title and tagline add below given CSS.

For this go to Admin Panel > Appearance > Customize > Additional CSS and paste the CSS.

.site-title {
    font-size: 3em;
}

.site-description {
    font-size: 15px;
}

Hope this helps.

Best Regards!!

Hello @tompearse,

Glad we could help you.

If you have any issues further then please let us know.

Further, we would really appreciate if you could help us by rating our theme by following the link given below:

https://wordpress.org/support/theme/trade-line/reviews/

Thank you.

Regards!!