The dashboard viewer supports many themes, chosen through the options object from the StiViewerTheme enumeration.

In Vue.
<script setup lang="ts">
import { Viewer, Stimulsoft } from 'stimulsoft-dashboards-js-vuejs/viewer'

var report = new Stimulsoft.Report.StiReport();
report.loadFile("Dashboards/Dashboard.mrt");

var options = new Stimulsoft.Viewer.StiViewerOptions();
options.appearance.theme = Stimulsoft.Viewer.StiViewerTheme.Office2022WhiteViolet;
options.appearance.fullScreenMode = true;
</script>

<template>
    <Viewer :report="report" :options="options" />
</template>

How it works. The theme is a viewer option, so one assignment reskins the entire preview.