Hope this help.

Works for Odoo 17

/** @odoo-module **/

import { registry } from "@web/core/registry";
import { WebClient } from "@web/webclient/webclient"
import {patch} from "@web/core/utils/patch";
import { useService } from "@web/core/utils/hooks";

// Changes Odoo to My Title
patch(WebClient.prototype,  {
    setup() {
        super.setup();
        const titleService = useService("title");
        titleService.setParts({ zopenerp: "My Title" });
    },
});

Hi,
You can use the following code.

** @odoo-module **/

import { registry } from "@web/core/registry";
import { WebClient } from "@web/webclient/webclient"
import {patch} from "@web/core/utils/patch";
import { useService } from "@web/core/utils/hooks";

// Changes Odoo to My Title in window title
patch(WebClient.prototype, {
setup() {
super.setup();
const title = useService("title");
title.setParts({ zopenerp: "My Title" });
},
});

Hope it helps

From /odoo/addons/web/static/src/webclient/webclient.js
in community modules version 17

U could Find line

 this.title.setParts({ zopenerp: "My custom Tite" }); // zopenerp is easy to grep

u could replace "My  custom Title " to ur title and the upgrade module with technical name web

Does not working 

Consider directly overriding the setTitleParts method within the patch to have more control over title construction.

Example:

patch(WebClient.prototype, { 'legion_hide_odoo_tab.WebClient': { setTitleParts(parts) { parts = parts.filter(part => part.name !== 'zopenerp'); // Remove 'zopenerp' part this._super(parts); } } });