The embassy in the U.K. ask for these documents also but you don’t have to go on that flight or 100% stay in that hotel. It’s the COE info that matters
U.K. embassy. For my visa I had booked a flight but then I changed my date. The flight number and date on the COE is what needs to match. You don’t even need to have a booked flight for the visa in the U.K. you can just send a screenshot of the flight details of the one you are thinking of taking