Shopify Collection Tag Duplication Issue

Hi Guys,

The content of our collection pages are duplicated to the "tag" pages based on Google SERPs.

Example:
https://www.example.com.au/collections/dresses (main category)
https://www.example.com.au/collections/dresses/cocktail (tag page)

There's quite a lot of tag pages so we are looking for the best solution.

Our current solution is to de-Indexing of the filter/tag pages using meta noindex tag.

Step 1: Amend a snippet of code within the theme.liquid inside the head element.

Step 2: Replace <link rel="canonical" href="{{ canonical_url }}" />

with the following bit of code:

{% if template contains 'collection' and current_tags %} <meta name="robots" content="noindex" /> <link rel="canonical" href="{{ shop.url }}{{ collection.url }}" /> {% else %} <link rel="canonical" href="{{ canonical_url }}" /> {% endif %}

Are the above steps would suffice and fix the duplication issues in the SERPs?
Or do we need to add a Step 3: Canonicalise filter/tag pages to their main category pages - straight up canonicalising all tag pages pointing to their respective main categories.