I guess you are looking for something like this: https://www.mathworks.com/matlabcentral/fileexchange/24576-inplacearray-a-semi-pointer-package-for-matlab
Also check the discussion on this question: https://www.mathworks.com/matlabcentral/answers/370282-is-it-possible-to-create-a-sub-array-without-using-additional-memory-on-matlab
As an alternative, you might also look into matfile() if the file is already saved in a mat file.