Google on indexing a non-canonical URL even if we use 301 redirect?

I implemented 301 redirects for a page and it’s working fine the page is being redirected to the new URL but google is not selecting the new one as a canonical URL and it is indexing not only the new one but also the old page what should be done that google will choose a new page as a canonical URL.

What are Canonical URLs:

A canonical URL is the URL of the page that Google thinks is most representative of a set of duplicate pages on your site. For example, if you have URLs for the same page one is company.com?dress and the other is company.com/dresses here google will choose one as canonical.

If you don’t tell Google which URL is canonical, it will make the decision for you, or it can treat them equally, which may lead to unwanted behavior, as stated in Why should choose a canonical URL?

If you have two similar pages, and they are both eligible to rank for a certain keyphrase, the search engine simply doesn’t know which of the two URLs it should send the traffic to. To solve this, you can select a preferred URL, this is what we call the canonical URL.

What should we do to remove non-canonical or duplicate URLs?

When it comes to canonicals google essentially recognize that these two pages are equivalent and then google try to pick one of them to show in the search results there is no ranking advantage from having this one or the other one showed it’s purely a matter of which one is shown in the search results and which one is used for attribution in search Console.

John Mueller was asked about canonical URL. He explained the process of search results.

John Mueller:

“It’s not super critical but when it comes to canonicalization google uses redirects as one signal but google also uses other signals as well like internal links, sitemap files, external links. All of the explanation that you have across your pages all of that can play in and it can happen that you redirect one page to another page but google systems say the canonical should remain the original URL and the way that you can help google to switch and make sure that everything is aligned that all of your internal links are pointing at the new URL your external links are pointing at the new URL in the sitemap file.“

All of the explanation that you have you always point to the new URL and then when google look at the bigger picture google see pretty clear you want that one indexed and so google will focus on that one but there’s no ranking change or anything so there is not anything critical that you need to do.

Similar question was asked to John Mueller: