Need to read a message on Telegram, but don’t want the other person to know? For example, if you are going to check important information without the obligation of an immediate response, or want to prepare for a conversation in advance. Use three simple ways to do this.
Use chat preview
This feature is available in the app for iOS and Android. It allows you to read messages in secret from the sender in both private chats and Telegram channels.
To read a message in secret from the other person, on the main screen, hold the icon with the avatar to the left of the interlocutor’s name or channel. A reduced dialog window with the chat and settings menu will open.
All messages can be read in miniature by scrolling through the dialog. To close the mini chat window, leaving messages “unread”, tap on the free space next to the settings menu. Be careful: if you tap on the dialog window itself, it will fully unfold, and all messages will become read.

Note: in the settings menu, you can mark all messages as read.
Read Push Notifications
Perhaps Push Notifications are the simplest way to read a message in secret from its sender in both iOS and Android apps, as well as on the desktop version. To see notifications, go to Telegram settings, select “Notifications and Sounds.”

Then choose the sections whose notifications you would like to see. For example, you can enable them for all personal chats, groups, channels, stories, or for reactions to messages and stories. Or turn off all notifications, leaving only exceptions.

Suppose you want to see push notifications about messages only from certain interlocutors or channels. For this, disable all notifications, and then tap on “Personal chats” and add exceptions. In the settings, enable “Show text.”

Now, in push notifications, you will see the full text of the entire message, while for the other person, it will be marked as unread.
Synchronize Smartphone and Smart Watch
Another way to read messages in secret from the sender is to synchronize the smartphone with a smart watch or smart bracelet. Push notifications will be sent to the smart watch. You will read them, and the message will be marked as unread for the other person.
Note: depending on the model and screen size, you may not see the entire message, only a part of it.