It really depends on your project & how your code is split up. A lot of business type logic code should be identical. I've migrated a couple decade plus old we

It really depends on your project & how your code is split up. A lot of business type logic code should be identical. I've migrated a couple decade plus old web form projects. A lot of the business logic can be moved to .NET Core 6 verbatim. I'll often set up a new version & slowly proxy web requests from the old site to a new version of the site as we update it.