Can you change the appearance of apple mail

Yes, you can customize the appearance of Apple Mail on your Mac or iOS device. Here are some ways to do so:

Mac:

Change the theme: Go to Mail > Preferences > General, and select a theme from the "Theme" dropdown menu. You can choose from a variety of themes, including Dark, Light, and a few other options.
Customize the font: Go to Mail > Preferences > Fonts, and select a font and font size from the dropdown menus.
Change the layout: Go to Mail > Preferences > Viewing, and select a layout from the "Layout" dropdown menu. You can choose from a variety of layouts, including Compact, Detailed, and more.
Customize the toolbar: Go to Mail > Preferences > General, and click on the "Toolbar" tab. You can add or remove buttons from the toolbar, and customize their layout.
Change the background image: Go to Mail > Preferences > General, and click on the "Background" tab. You can select a background image or color from the dropdown menu.

iOS:

Change the theme: Go to Settings > Mail, and select a theme from the "Theme" dropdown menu. You can choose from a variety of themes, including Dark, Light, and more.
Customize the font: Go to Settings > Mail, and select a font and font size from the "Font" dropdown menu.
Change the layout: Go to Settings > Mail, and select a layout from the "Layout" dropdown menu. You can choose from a variety of layouts, including Compact, Detailed, and more.
Customize the toolbar: Go to Settings > Mail, and select "Edit" next to "Toolbar". You can add or remove buttons from the toolbar, and customize their layout.
Change the background image: Unfortunately, you cannot change the background image on iOS devices.

Additional tips:

You can also customize the appearance of Apple Mail by using third-party themes and plugins, such as MailTheme or MailStyle.
If you're using a dark theme, you can also customize the appearance of the mailboxes and folders by going to Mail > Preferences > General, and selecting a dark theme for the mailboxes and folders.
You can also customize the appearance of Apple Mail by using CSS stylesheets. For more information, see Apple's documentation on customizing Mail using CSS.