Designing a scalable messenger similar to Telegram

It is required to develop an architectural solution for a messaging service that includes core features: personal dialogues and group chats (up to 500 participants), transmission of text messages and media files, persistent storage of history with search query support, display of online status, and push notifications. The system must withstand a load of 500 million active users per day (DAU) and process about 25 billion messages daily.