A professional SEO company can give suggestions to companies, or individuals for site migration that are also discussed below. If you’ve already opted for some SEO packages, or any other service, from an SEO agency and are in the middle of the SEO process and want a site migration, they can aid you, in that case, as well. However, if you want to get a site migration done on your own, there are a bunch of factors you should consider while executing site migration, some of which are discussed here  - https://www.ezrankings.org/blog/website-migration-without-losing-traffic/