As John noted there is no "digital zoom" on this better quality DSLR such as you will find on a lot of lower end cameras, you will need a quality "zoom" lens (or use your feet to zoom) to do this AND the high quality end result is the reason for this optical rather than digital zoom approach. You can enlarge the image via cropping later but the quality will be lower than if the lens and camera position were used to fill as much of the frame (and the sensor area) as possible when taking the image. The proper lens for the combination of distance and desired subject matter lets you capture the best image.
Once you capture the image you can only lose, not add, useful original data. Your 750D requires a different technique to get the desired image compared to simpler cameras but when you use the right technique the resulting image will easily exceed the quality provided by the simpler camera. The time you spend learning how to best utilize your new camera will pay huge dividends with the results achieved and most new DSLR users will never approach the capability limits of their camera but those who put in the time and effort will be pleased that they did.
Rodger
EOS 1DX M3, 1DX M2, 1DX, 5DS R, M6 Mark II, 1D M2, EOS 650 (film), many lenses, XF400 video
