How to add "Show All" link to existing pagination

Client wants me to add a “Show All” link beside the existing pagination (see this page: https://carolinabowties.com/category/all-ties/. I need the pages to paginate as they do now, but also add the link for those who want to see everything on one page. I’ve seen a few posts here about adding code to the functions file, but I’m not sure how to get this to appear/work on the page template file (it’s the product category template). The product posts are sorted by category. Any help would be appreciated.