Overriding User-Agent in WebView

I’m trying to request the desktop version of a site by setting the User-Agent header. When I inspect the headers that are sent the UA header is still the default Safari user agent.

const ua = 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_4) AppleWebKit/604.3.5 (KHTML, like Gecko) Version/10.1 Safari/602.1 EdgiOS/45.8.14';

const wv = new WebView();
const url = 'https://manytools.org/http-html-text/http-request-headers/';
const request = new Request(url);
request.headers = { 'User-Agent': ua };
await wv.loadRequest(request);
await wv.present(true);

I have this same question, is no one able to answer this? Is it even possible to set the User Agent in a Web View?