Should be as simple as
conda install -c conda-forge fenics-dolfinx mpich petsc=*=complex*
which is mentioned several times in this forum, for instance at Conda install dolfinx for complex-valued problem
Should be as simple as
conda install -c conda-forge fenics-dolfinx mpich petsc=*=complex*
which is mentioned several times in this forum, for instance at Conda install dolfinx for complex-valued problem