Oppo
Turn Web Link Previews On or Off auf Oppo
Web link previews in the Messages app pull a small snapshot of the linked page - title, image, and sometimes a short description - and display it directly inside the conversation. This happens automatically whenever the app recognizes a URL in a sent or received text, but only if the underlying setting allows it.
On Oppo devices this behavior is controlled from within the Messages app itself, not from the general system settings. If previews are missing, either the feature got turned off at some point, or it was set to load previews only for select messages instead of all of them.
Where to change it
Open Tap on Messages ➔ Open the Menu ➔ Tap on Settings ➔ Tap on General ➔ Tap on Automatic previews ➔ Enable or disable Show all previews.
Turning this on loads a preview for every recognized link automatically. Turning it off stops previews from generating, so links appear as plain text only, which loads faster and avoids sending a request to the linked website before you decide to open it.
If you only want to save mobile data instead of blocking previews completely, check whether your Messages app has a separate option to limit preview loading to Wi-Fi. Not every Oppo device offers this, so the toggle above remains the main control.