@Puneet already answered. The zoom is due to EIS (which can't be disable unfortunately)
If there is no zoom in 4K like @user1526673240090 point it out, it's because there is no EIS in 4K. All other video resolutions have EIS on.
Please @user1525532364262 mark this thread as answered. Some people ask a question, another give the answer/solution and the OP never come back to close the thread (and/or to say thank you).