How to maintain positions in the search results with a radical change in the design of the site?

Question

Search Engine Optimization

Good afternoon!
There is a request for a radical change in the corporate identity of the company - a website, applications, attributes, etc.
Now the site occupies a place on the first page of search results (google and Yandex).
The specifics of the company's work involves orders and interaction with customers mainly through the site.
The site is hopelessly outdated.. the request is to update the design concept.
Tell me, plz - how to make such drastic changes so that the site remains in its previous positions in the search results? Is this in principle possible?
Which options are correct and more viable:

• Move the site to a new engine / design, but roughly keep the site structure and content for the pages? (there is such a possibility)
  
• If we radically change the design: a multi-page site from the early 00s -> modern landing?
  

Answer 1

Good afternoon!
1. “Move the site to a new engine / design, but roughly keep the site structure and content for the pages? (there is such a possibility)»
This option is more realistic in terms of maintaining current positions and search traffic in general.
To minimize the risk of traffic loss, you need to:
Provided that you complete all the above work, there is still some risk of traffic subsidence by about 20%. But this situation will be corrected in 1-2 months.
2. “If you change the design dramatically: a multi-page site from the early 00s -> modern landing?”
Such a case is generally not welcome if you want to drive traffic from search. One-page landing will be effective only for contextual advertising. SEO in this case is not effective, only if the brand queries for which your site will be vital.

Answer 2

Search engine algorithms are currently complex and unpredictable. It is likely that after a certain time the search engine will return the changed pages to their original place in the search results, but no one can guarantee this. You should not radically change the site without good reasons. If there are such reasons, then at first it is necessary to analyze the problem areas, paying special attention to external links, internal linking and the compliance of the new content with the seo-structure of the site.
It is desirable: to keep, if possible, the old structure of the site pages;
Map 301 redirects;
Set up page redirects from old URLs to new ones;
Save all site text content and metadata;
Check the internal linking of the site and make sure that all important pages of the site receive enough weight;
Make sure the site is mobile friendly;
Optimize page loading speed;
Analyze the convenience of the site for users.