How to transfer a site to a new cms without losing positions?

Question

CMS

Hello, how to change the old cms to the new one? Now the old site is working, we made a new site for ourselves, it hangs on a subdomain closed from indexing, filled it with everything that was on the old one, now how to make a replacement so that positions in the search do not sink?
What I already know from the search and tips, correct me if I'm not mistaken:
In order for me to change cms and not lose positions, I must save the url of the pages and the meta description, regarding the 301 redirect, I really doubt that it needs to be done, even to be honest, having all the instructions, I don’t quite understand how to work with it, because I just need to do the full replacement with a new cms where everything works as I need, i.e. I was advised to register a 301 redirect on the old site where there will be an old link with a redirect to a new one, but why should I redirect the link to a new one when I do a cms replacement, the domain is not will change or is it necessary for search engines? To make an explanation that the links differ from the old ones in terms of the samedomain/product1 and the samedomain/product11 type? If there is an opportunity to help me with this, if you have done this repeatedly, then I will be grateful (not free)

Answer 1

It is necessary that all paths match, or there is a redirect from old to new.
And in terms of content, so that there are not strong changes. If you wish, you can save both positions and traffic, transferred to another CMS many times.

Answer 2

The search engine knows that such and such a link has such and such content and stores this link.
If you save all the links on the new CMS, then everything will be ok, the search engine does not care about the CMS at all.
If some links have changed, then it is necessary to explicitly indicate that there was such a url - it has become such. For these purposes, 301 status is used. It literally means this page has moved to a new address.

Answer 3

If the urls of all pages on the new site match the old ones, then no redirects should be done.