Read two lines at a time and concatenate them. Use /s on the regex to allow '.' to match the newline.

#! perl -slw
use strict;

m[red line.*location (\S+) (\S+)\n]s and print "($1, $2)" 
    while $_ = <DATA> . <DATA>;

__DATA__
A red line is found
at location 2.5 4.5
A Blue line is found
at location 2.6 4.5
A red line is found
at location 2.67 4.56
The red arc is found
at location 2.5 4.5
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