Open HoYoLAB and login if you haven't
Open dev tool (Ctrl+Shift+I or right click > Inspect)
For Chrome/Opera (or other Chromium based) users, click on the Application tab. If not found, click on the arrow (>>).
For Firefox, click on the Storage tab.
On the filter box, type v2. You might want to expand the dev tools to see clearly.
Find ltoken_v2 and ltuid_v2, click on them, and copy the value.