How to Obtain the Embed Code for Web Chat for the Website:
Copy the embed code from Sites > Chat Widget > Select > Get Code
Here are Detailed Steps on How to Add a Custom Chat Widget to a Shopify Website using Different Methods
Log in to your Shopify account: Go to your Shopify account and log in.
Navigate to the "Online Store" section: From your Shopify dashboard, navigate to the "Online Store" section.
Edit your website's theme: Select the theme that you want to edit and click on the "Actions" button. Choose "Edit code" from the drop-down menu.
Open your theme's theme.liquid file: In the list of files that appears, select the "Layout" folder and then select the "theme.liquid" file.
Paste the embed code: Locate
</body>the tag within the theme.liquid, then add embed code above it.
Save the changes: After adding the embed code, hit the save button.
Preview the chat widget: Go to your website and refresh the page. The chat widget should now be visible on your website.
Please test it out to make sure it's working correctly.