我猜你将不得不求助于抓取scss版本的主题定义，并根据自己的喜好提取调整后的值。scss源代码似乎没有与材料分发捆绑在一起，所以请转到https://github.com/angular/components/blob/master/src/material/core/theming/prebuilt/purple-green.scss查看其源代码。然后：
my-custom-theme-definition.scss

@use '@angular/material' as mat;

// taken from https://github.com/angular/components/blob/master/src/material/core/theming/prebuilt/purple-green.scss

// Define a theme.
$my-custom-primary: mat.define-palette(mat.$purple-palette, 700, 500, 800);
$my-custom-accent: mat.define-palette(mat.$green-palette, A200, A100, A400);

$my-custom-theme: mat.define-dark-theme((
        color: (
                primary: $my-custom-primary,
                accent: $my-custom-accent
        )
));

my-custom-theme.scss（在globalstyles.scss中导入一次）

@use '@angular/material' as mat;
@import './my-custom-theme-definition';

// IMPORT ONLY ONCE, AS ALL STYLES ARE BEING OUTPUT

// Include non-theme styles for core.
@include mat.core();

// Include all theme styles for the components.
@include mat.all-component-themes($my-custom-theme);

other-component.scss

@use 'sass:map';
@use '@angular/material' as mat;

@import 'my-custom-theme-definiton';

$hue: 700; // or 50 or some key defined in any palette definition https://github.com/angular/components/blob/master/src/material/core/theming/_palette.scss

.chat-header {
  color: mat.get-color-from-palette(map.get($my-custom-theme, primary), $hue); 
}