开发工具：vue3 ts vite 

如上图，选择个颜色整个变化，如下图

默认主题为绿色

切换成其它色。

这里面的颜色块，你也可以给个取器色组件，可切换成任意色。切换时主要执行下方的方法，有兴趣可自己研究下。

/**

* 切换主题颜色

*/

const changeThemeColor = (color: string) => {

document.documentElement.style.setProperty("--el-color-primary", color);

document.documentElement.style.setProperty("--el-color-primary-dark-2", `${getDarkColor(color, 0.1)}`);

for (let i = 1; i <= 9; i++) {

document.documentElement.style.setProperty(`--el-color-primary-light-${i}`, `${getLightColor(color, i / 10)}`);

}

}

1 创建hooks

// 文件：src/hooks/useTheme.ts
// import { useTheme } from "@/hooks/useTheme"; //引入主题勾子
// const { changeThemeColor } = useTheme(); // 解构功能

import { ElMessage } from 'element-plus'

/**
 * 颜色转换函数
 * @method hexToRgb hex 颜色转 rgb 颜色
 * @method rgbToHex rgb 颜色转 Hex 颜色
 * @method getDarkColor 加深颜色值
 * @method getLightColor 变浅颜色值
 */
export function useTheme() {
  // str 颜色值字符串
  const hexToRgb = (str: string): any => {
    let hexs: any = ''
    let reg = /^\#?[0-9A-Fa-f]{6}$/
    if (!reg.test(str)) {
      ElMessage.warning('输入错误的hex')
      return ''
    }
    str = str.replace('#', '')
    hexs = str.match(/../g)
    for (let i = 0; i < 3; i++) hexs[i] = parseInt(hexs[i], 16)
    return hexs
  }
  // r 代表红色 | g 代表绿色 | b 代表蓝色
  const rgbToHex = (r: any, g: any, b: any): string => {
    let reg = /^\d{1,3}$/
    if (!reg.test(r) || !reg.test(g) || !reg.test(b)) {
      ElMessage.warning('输入错误的rgb颜色值')
      return ''
    }
    let hexs = [r.toString(16), g.toString(16), b.toString(16)]
    for (let i = 0; i < 3; i++) if (hexs[i].length == 1) hexs[i] = `0${hexs[i]}`
    return `#${hexs.join('')}`
  }
  // color 颜色值字符串 | level 变浅的程度，限0-1之间
  const getDarkColor = (color: string, level: number): string => {
    let reg = /^\#?[0-9A-Fa-f]{6}$/
    if (!reg.test(color)) {
      ElMessage.warning('输入错误的hex颜色值')
      return ''
    }
    let rgb = useTheme().hexToRgb(color)
    for (let i = 0; i < 3; i++) rgb[i] = Math.floor(rgb[i] * (1 - level))
    return useTheme().rgbToHex(rgb[0], rgb[1], rgb[2])
  }
  // color 颜色值字符串 | level 加深的程度，限0-1之间
  const getLightColor = (color: string, level: number): string => {
    let reg = /^\#?[0-9A-Fa-f]{6}$/
    if (!reg.test(color)) {
      ElMessage.warning('输入错误的hex颜色值')
      return ''
    }
    let rgb = useTheme().hexToRgb(color)
    for (let i = 0; i < 3; i++) rgb[i] = Math.floor((255 - rgb[i]) * level + rgb[i])
    return useTheme().rgbToHex(rgb[0], rgb[1], rgb[2])
  }

/**
 * 切换主题颜色
 */
 const changeThemeColor =(color: string)=> {
  document.documentElement.style.setProperty("--el-color-primary", color);
  document.documentElement.style.setProperty("--el-color-primary-dark-2", `${getDarkColor(color, 0.1)}`);
  for (let i = 1; i <= 9; i++) {
    document.documentElement.style.setProperty(`--el-color-primary-light-${i}`, `${getLightColor(color, i / 10)}`);
  }
}


  return {
    hexToRgb,
    rgbToHex,
    getDarkColor,
    getLightColor,
    changeThemeColor
  }
}

2 创建抽屉组件，我的项目中是用到‘el-drawer’，实际上可根据自己的情况走。

<!-- 位置 子组件：components/layout/ComSetting.vue -->
<template>
  <el-drawer class="drawer-setting" v-model="dialogVisible" :show-close="true" @closed="handleClosed">
    <template #header>
      <h4 class="title">设置</h4>
    </template>
    <template #default>
      <div class="body">
        <div class="b-box">
          <div class="title">主题更改颜色</div>
          <div class="fun">
            <div class="colors">
              <div class="item" v-for="(item, index) in colors" :key="index" :style="{ background: item }" @click="changeThemeColor(item)">{{ item }}</div>
            </div>
          </div>
        </div>
      </div>
    </template>
  </el-drawer>
</template>

<script setup lang="ts">
import { ref, reactive, defineProps, defineEmits } from "vue";

import { useTheme } from "@/hooks/useTheme"; //主题更改
const { changeThemeColor } = useTheme();

let emits = defineEmits(["update:opened"]);
let props = defineProps({
  opened: {
    type: Boolean,
    default: false,
  },
});

let colors: any = reactive(["#36CEBF", "#f5222d", "#fa541c", "#722ed1"]);

//对话框开关
let dialogVisible: any = computed({
  get() {
    return props.opened;
  },
  set(val) {
    emits("update:opened", val);
  },
});

let settingOpened = ref(true);

//设置
function handleSetting() {
  settingOpened.value = !settingOpened.value;
}

//关闭事件
function handleClosed() {
  //emits("update:opened", false);
}
</script>

<style lang="scss" scoped>
//@import '引入的css文件';
.drawer-setting {
  .title {
    font-size: 14px;
  }
  .body {
    .b-box {
      min-height: 50px;
      .title {
        height: 40px;
        line-height: 40px;
        color: #000;
      }
      .colors {
        display: flex;
        justify-content: start;
        .item {
          width: 20px;
          height: 20px;
          display: inline-block;
          border-radius: 4px;
          margin-right: 16px;
          cursor: pointer;
        }
      }
    }
  }
}
</style>

3 引用该组件，并运行即可。