Custom Request Headers
To add custom request headers to your website, open the debugging panel, and go to the Headers tab.
Here, you can add a key-value pair, and optionally, label different headers that use the same key. You can add as many custom headers as you want, and disable individual key-value pairs using the toggle on the left.
The custom headers will apply to every new network request. To verify this, refresh the page, and go to DevTools → Network → Headers.