The fonts that come by-default with elementary OS do not support Urdu language text. So I had to install supporting font to render Urdu text properly.
Then, I go to Google Chrome settings, set Standard Font as
Noto Naskh Arabic UI (supporting font) and Urdu texts are rendered properly in Chrome. Similarly, I set system fonts (Window Title, Interface, Document, and Monospace) to
Noto Naskh Arabic UI using Gnome Tweaks. This makes Urdu text in the operating system's notification panel appear properly.
However, other apps (e.g. Ephiphany, Station, Rambox; I use the later two apps to use Whatsapp and Facebook Messenger on the laptop) still do not render Urdu text properly. There is no option to specify the fonts within these apps and they do not seem to import system fonts (set using Tweaks) themselves.
Is there a way I can force these apps to use system fonts?
By the way, here are two examples of what I mean from proper and improper Urdu text rendering.
Operating system: elementary OS 5.1.2
Laptop: Thinkpad E585
Edit: In Windows 10, Rambox renders Urdu text properly. So I think it imports system fonts there and system fonts of Windows 10 by-default support Urdu.