Hello @zarmayana,
To make the price size smaller paste below given CSS by going to Admin panel > Appearance > Customize > Additional CSS.
.trip-price {
font-size: 20px;
}
You can adjust the px as per your requirement.
Now to adjust the formatting of the price as you have mentioned you have to add below given code in your child theme’s functions.php file.
If you have not activated the child theme yet then you can create and activate the child theme using the plugin give below:
https://wordpress.org/plugins/wp-child-theme-generator/
After activating the child theme in your child theme functions.php file add below given code:
https://gist.github.com/anonymous/427cae013130488a403749112a060307
Hope this helps.
Best Regards!!