How to find the Endnote template for CJPH submission? I have been searching and trying out to find the Endnote citation style to match the one required for the Canadian Journal of Public Health submission for hours, with no success.

It demonstrated that the CJPH style here. It also mentioned that "The style for references is based on the ICMJE Recommendations." I have looked up and searched for the endnote citation template for keywords related to CJPH and ICMJE, but I couldn't find the the one that matches.
From the wikipedia page of the ICMJE Recommendations, it looks like the citation style you need is some implementation of the well-known Vancouver system. You should already have a few different versions of it, as I think they are part of the standard EndNote installation. If not, you can easily find and download them from the Internet.

I would then choose the one that looks the most similar to what your journal asks for, and do the (hopefully) minor modifications necessary to make it exactly as the journal requires. You can find plenty of online resources about  citation-style editing in EndNote. This one, for example, seems to be a nice introductory video that might be useful, if you don't have any previous experience.