How to add an event code to the conversion page?

Question

Google Ads

Hello
, I want to add a conversion tracking tag from Google to a page. the instructions say:
Add the event code to the conversion page. This is the page that site visitors land on after they complete a conversion, such as with a "Thank you for your purchase" message.
1. Open the HTML code of the conversion page.
2. Copy the code snippet below and paste it between the head() tags right after the global tag.
As I understand it, it should be inserted between the head tags only on the page where I want to track, but how can I do this so that it is reflected only on one page (head is a template, cms opencart)?