Google Tag Manager Ecommerce Enhancement conversation on Shopify Website

Nowadays all clients asking for Ecommerce customer Enhancement update to capture data at Google Tag Manager Layer

First, we have to put theGlobal site tag on the theme.liquid

<!-- Global site tag (gtag.js) - Google Ads: 11111111 -->
<script async src="https://www.googletagmanager.com/gtag/js?id=AW-11111111"></script>
<script>
  window.dataLayer = window.dataLayer || [];
  function gtag(){dataLayer.push(arguments);}
  gtag('js', new Date());
  gtag('config', 'AW-111111111', {'allow_enhanced_conversions':true});
</script>

Below whole code we have to put on Shopify admin.
Setting ➔ Checkout ➔ Order processing

https://yourdomain.myshopify.com/admin/settings/checkout

enhanced_conversion_data variable where you have to add all additional details which you require

<!-- Global site tag (gtag.js) - Google Ads: 11111111 -->
<script async src="https://www.googletagmanager.com/gtag/js?id=AW-11111111"></script>
<script>
  window.dataLayer = window.dataLayer || [];
  function gtag(){dataLayer.push(arguments);}
  gtag('js', new Date());
  gtag('config', 'AW-111111111', {'allow_enhanced_conversions':true});
</script>

<script>
  var enhanced_conversion_data = {
    "email": '{{ customer.email }}',
    "phone_number": '{{ customer.phone }}',
    "first_name": '{{ customer.first_name }}',
    "last_name": '{{ customer.last_name }}',
    "home_address": {
      "street": '{{ shipping_address.street }}',
      "city":'{{ customer_address.city }}',
      "region": '{{ customer_address.country_code }}',
      "postal_code": '{{ customer_address.zip }}',
      "country": '{{ customer_address.country }}'
    }
  };
</script>

{% if first_time_accessed %}
<!-- Event snippet for Purchase conversion page -->
<script>
  gtag('event', 'conversion', {
   		 'send_to': 'AW-111111111/xxxxxxxxxxxx',
  		 'value':    {{ checkout.subtotal_price | divided_by: 100.0 }},
       'currency': '{{ currency }}',
       'transaction_id': '{{ order_number }}'
       });
</script>
{% endif %}