From the https://www.emacswiki.org/emacs/EndOfLineTips
You can reopen the file with the correct line ending with a command like
M-x revert-buffer-with-coding-system utf-8-dos. If your file is not in Unicode, be sure to specify the correct encoding system instead of
CR+LF end of line, when UNIX uses only
CR sometimes looks like
^M. For viewing
^M you must use
M-x revert-buffer-with-coding-system utf-8-unix. This will use
LF as end of line and indicate
^M instead of Dos which uses
CR+LF as end of line.
Disable autodetect: not sure it needs. If you want to convert files into UNIX format, then open DOS file and set line ending with
M-x set-buffer-file-coding-system utf-8-unix, this command will convert all
If you can edit the file, you could open file with a certain coding system with
-*- coding: utf-8-unix; -*- at the first or second line in the file.