I need to add one item in content tree and instead of clone it in different places in content tree, i want to use canonical link for SEO Optmization.
Is there any steps/documents how to handle this in SXA 1.6?
As an example, you may want to look at the Sitecore SXA Storefront.
If you create your storefront site using the Commerce Storefront Template feature, then a canonical URL is automatically included in the metadata for every storefront page.
If you create your own page designs, you can insert the Commerce Metadata meta rendering from the SXA toolbox in your page designs in order to assign canonical URLs to every page.
If you cannot use these templates, then you may want to create your own custom ones based on them.