Based on your example, you want to run another perl script from within your perl program, and have it present its output in a separate cli window, then this maybe what you are looking for.

my $filename = 'some perl script (potentially with spaces).pl';

system qq[ start cmd /k perl "$filename" ];
[download]

Using qq// for the outer set of quotes removes the need to escape the inner ones needed around the filename whilst still allowing $filename to be interpolated. See Quote-like operators for more info.

Using /k will ensure that the window remains and the script output is visible after the command has ended.