The official AMP plugin for WordPress enables AMP support but has very limited customization features. Currently, all you can do is change the background color for header, link and enable it for custom post types on your website.
There are some more AMP plugins and add-ons which you can install on your WordPress website in addition to the main AMP plugin to activate more customization options.
Yoast SEO users can use Glue for Yoast SEO & AMP plugin. It makes sure your meta-data is implemented correctly on AMP version of your website.
Next, to the technical SEO improvements, the plugin provides you an easy way to customize your AMP pages – By adding rudimental styling in the form of colors and link styles, so that your AMP powered pages can keep up the feeling of your main website pages.
You can change your AMP page design from SEO -> AMP, and look at the design tab. Apart from this, the plugin also allows you to upload a custom logo select a default header image to use when post featured image is not set.
There are more plugins available in WordPress plugin repository offering you more AMP customization options, you can check them yourself by searching AMP on your WordPress plugin installer page or visit AMP extensions page here.
After you install any new plugins and customize AMP options on your website, make sure to validate your AMP version, to check if your AMP pages are valid.