First of all thank you very much for using the theme.
Yes, you can definitely add the custom CSS for changing the color of different parts of the section by going to Admin Panel > Appearance > Customize > Additional CSS.
But since different parts require different custom CSS so the CSS to be included will be long so you can go through the child theme instead. You can add any amount of custom CSS to your child theme style.css.
Hope this helps.
PS: Please create your own ticket so that it would be easy for us to follow up your answers.
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