GP here. I said by default it’s not there. There’s the “secret chats” feature that is E2EE, but it has to be explicitly chosen by the user. The default chats are stored on Telegram’s servers in a way Telegram can decrypt those. Secret chats are also tied to a single device. There is no “secret chat”/E2EE available for group chats, unlike in Signal.

By default there's no encryption and in order to have an encrypted chat you need to initialize it manually from the contact menu and IIRC it's not available on desktop - you won't initialize it from PC nor it will be synchronized with