Take a step back. Start from a simple thing. Add one feature at a time, always test it didn't break. If you change several things at once, you don't know exactly which one is the culprit. For example, start with an empty page. Then add a form. Once it works, add calling the rest client. Once it works, add the spreadsheet. It's not a weakness to progress in small steps, it's a method that one needs to learn. You'll see it leads to the results faster than trying to write everything at once, in the end.

Sir, Please check my existing code, Yes, I am trying to do what you have explained, Can you please let me know how i can utlize my nested sub for calling my api?

#!/usr/bin/env perl
package Op;
use strict;
use warnings;
use Win32::Process;
##use Net::LDAP;
use REST::Client;
use JSON::Parse ':all';
use MIME::Base64;
use Term::ReadKey;
use Data::Dumper;
use MIME::Lite;
use Net::SMTP;
use Spreadsheet::XLSX;
use Spreadsheet::ParseXLSX;
use Excel::Writer::XLSX;
use Config::Properties;
use Data::Dumper;
use List::Compare;
use Array::Compare;
use Storable qw/freeze/;
use Data::Validate::IP;
use Data::Table::Excel;
use Excel::Writer::XLSX::Chart;
use Win32::OLE::Const; 
use Spreadsheet::WriteExcel::Utility qw( xl_range_formula );
use Win32::OLE;
use POSIX 'strftime';
use POSIX qw(strftime);
use DateTime;
use DateTime::Format::Strptime;
use Try::Tiny;
use feature qw{ say };

open my $fh, '<', "C:/PERL/" . "config.properties" or die "unable to o
+pen configuration file";
my $properties = Config::Properties->new();
$properties->load($fh);
my $value = $properties->getProperty('oktapreview.token');
my $baseurl = $properties->getProperty('oktaQA.baseURL');
my $from_address = 'chandan@aol.com';
my $to_address = 'chandan@bol.com';
my $subject = 'A message with 2 parts ...';
my $my_file_zip = 'C://PERL//';
my $mail_host = 'mail.aol.com';
my $pass = '1234567';



sub result {
    
    my ($args) = @_;
    my $appID   = $args->{APPID};
    my $datver   = $args->{datetime};
    my $email   = $args->{Email};
    my $date = strftime '%Y-%m-%d-%H-%M-%S', localtime;
    my $date3 = strftime '%Y-%m-%d' , localtime(time() - $datver*60*60
+);
    my $date4 = strftime '%Y-%m-%d' , localtime(time() - 24*60*60);
    my $apiurllog = $baseurl ."/users/sys/logs?";
    my $client = REST::Client->new();
    my @responsetext;
    my @responsetextall;
    my $sortor = "filter=eventType+eq+%22";
    my $filter = "all.auth.sso";
    my @responsalter;
    my $target = "%22+and+to.id+eq+%22";
    my $strExcelFilename;
    my %header1 = (
             -size => 10,
        );
    
    sub api_call {
  $client->addHeader('Authorization',"SSWS $value");
  $client->addHeader('Accept','application/json');
  $client->addHeader('Content-type','application/json');
  $client->GET($_[0]);
}

my $date2 = "%22&since=" . $date3 . "T00%3A00%3A00.000-04%3A00&until="
+ . $date4 . "T23%3A59%3A59.000-04%3A00";

my $urlstringlog = $apiurllog . $sortor . $filter . $target . $appID .
+ $date2;

$strExcelFilename = "C:/PERL/" . "My-File" . $date . ".xlsx";

my $your_file_zip = "My-File . $date . '.xlsx'";

api_call($urlstringlog);
@responsetext = parse_json ($client->responseContent());
push @responsetextall, @responsetext;

for my $i (0..$#responsetextall) {

for my $j (0..$#{$responsetextall[$i]}) {

 my $responseid = $responsetextall[$i][$j]{act}{UID};
 my $responsdisp = $responsetextall[$i][$j]{act}{Name};

push @responsalter,  $responseid ;
}

}

my $workbook  = Excel::Writer::XLSX->new( $strExcelFilename );
my $format_bold = $workbook->add_format( bold => 1, size => 10, top=> 
+1, bottom=> 1 ); 
        my $format2 = $workbook->add_format(%header1);
my $worksheet = $workbook->add_worksheet('UserSSO-Data');

my $r = 1;
my $r2 = 1;
my $r3 = 1;

 foreach my $j (0..$#responsalter ) {
            
                                $worksheet->write(0, 0, 'UserSSO-Total
+-Users' );
                                
            $worksheet->write($r2, 0, $responsalter[$j]);
            
        
            $r2 += 1;
        }
        
        
        
        $workbook->close;
print "Spreadsheet saved.\n";

## Mail Functionality

 my $msg = MIME::Lite->new (
   From => $from_address,
   To => $to_address,
   Subject => $subject,
   Type =>'multipart/mixed'
 ) or die "Error creating multipart container: $!\n";

$msg->attach (
    Type => 'text/csv',
    Encoding => 'base64',
    Path => $my_file_zip,
    Filename => $your_file_zip,
    Disposition => 'attachment'
 ) or die "Error adding $your_file_zip: $!\n";

 MIME::Lite->send('smtp', $mail_host, Timeout=>60,Auth=>'LOGIN',AuthUs
+er=>$from_address,AuthPass=>$pass,Port => 25, Debug => 1);
 
                 }
[download]

Define the sub outside of the other sub:

sub api_call {
    my ($client, $value, $url) = @_;
    $client->addHeader('Authorization',"SSWS $value");
    $client->addHeader('Accept','application/json');
    $client->addHeader('Content-type','application/json');
    $client->GET($url);
}
[download]

and call it like

api_call($client, $value, $urlstringlog);
[download]

map{substr$_->[0],$_->[1]||0,1}[\*||{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^*ARGV,3]