More on the above (correct) reply…
Migration Assistant works with macOS Lion OS X 10.7.5 and later.
Click or tap for details > Move your content to a new Mac - Apple Support
As stated above, either cabling directly, or working off a Time Machine backup of the old machine, or working from a Disk Utility disk image (clone) copy of the old machine on an external storage device, is preferred. I’d also tend to avoid the Wi-Fi migration path, as that path is both slow, and prone to glitches if your Wi-Fi is at all unstable.
You will not have access to your existing 32-bit apps from High Sierra.
You might want to run the Go64 app on High Sierra before you upgrade, to see which apps you will need to update, upgrade, replace, or retire.
You will lose access to the 32-bit Office 2011 apps and earlier versions if you use Office for instance, and will need to upgrade to Office 2016, Office 2019, the upcoming Office 2021, the Office 365 subscription, or switch to LibreOffice app, or maybe migrate to the Apple iWork apps that can read and write many Office documents. Your Office documents will be migrated.