Use a dispatch table:

my @the_args = 0..5;

my %functions = (
  a => { 
    x => \&sub_a_text_x,
    y => \&sub_a_text_y,
  },
  b => {
    x => \&sub_b_text_x,
    y => \&sub_b_text_y,
  },
);

if( 
     exists $functions{$var1} 
  && exists $functions{$var1}{$var2}
) {
  $functions{$var1}{$var2}->(@the_args);
}
else {
  die "A horrible death";
}
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