I’ve documented the options here: DO CONCURRENT: compiler flags to enable parallelization - #6 by ivanpribec
According to an answer from Steve Lionel, quoted therein,
[ifx] will (attempt to) parallelize
DO CONCURRENTif you enable OpenMP, even if you don’t use OpenMP otherwise.
So the flag would be /Qopenmp on Windows. It is also documented in the Intel Fortran Compiler Reference page for DO CONCURRENT:
If compiler option
[qorQ]openmpis specified, the compiler will attempt to parallelize the construct.