• Send reactions to messages.
• Group and Channel admins can enable reactions in their chat via '...' menu > Manage > Reactions.
• Select text when typing and choose 'Formatting > Spoiler' in the context menu to hide some or all of the contents of a message.
• Click on the spoiler in chat to reveal its hidden text.
• Spoiler formatting hides text in chat, as well as in the chat list and notifications.