SwiftUI seems to be incomplete compared to what is provided by UIColor. The primary and secondary refers to the text colors, which are the UIColor.label and UIColor.secondaryLabel.

A simple extension to provide more UIColor:

public extension Color {
    static let lightText = Color(UIColor.lightText)
    static let darkText = Color(UIColor.darkText)

    static let label = Color(UIColor.label)
    static let secondaryLabel = Color(UIColor.secondaryLabel)
    static let tertiaryLabel = Color(UIColor.tertiaryLabel)
    static let quaternaryLabel = Color(UIColor.quaternaryLabel)

    static let systemBackground = Color(UIColor.systemBackground)
    static let secondarySystemBackground = Color(UIColor.secondarySystemBackground)
    static let tertiarySystemBackground = Color(UIColor.tertiarySystemBackground)

    // There are more..
}

However, a huge drawback is that the colors will not automatically change between light & dark modes.

The above code is only for iOS, while macOS/AppKit does not have corresponding lightText etc.

Therefore, a better solution is to define such colors in Assets Catalog.