# Perl 5, 17 + 2 (-pl) = 19 bytes

odd lines reversed

    $_=reverse if$.%2

even lines reversed

    $_=reverse if$|--


After @Martin's comment : input needs to have a trailing linefeed.

[try it online][1]


  [1]: https://tio.run/##K0gtyjH9/18l3rYotSy1qDhVITNNRU/V6P//xCSu5BQurvQMrn/5BSWZ@XnF/3ULcgA