$ perl -E 'my $x = "whateverstaticip_address=X"; say $x =~ /^.*static\s*ip_address=/ ? "YES" : "NO"'
YES

$ perl -E 'my $x = "whateverstaticip_address=X"; say $x =~ /^\s+static\sip_address=/ ? "YES" : "NO"'
NO