Unable to customize colors in installed themse

I have 2 blogs: https://www.therecoveringpessimist.me & https://www.snapshotstoryteller.com

I want to update the colors on both themes, but when I select Customize, all I see is the option for Widgets.

I’m not sure if it’s a plugin that clashing with the themes or something else, but it’s really odd.

Can someone help me please?