If like me you need to port some older projects using .NET Framework and Entity Framework to .NET 6 (or 7), then you might find it easier to do the change in two steps (or possibly even omit the 2nd step completely, although that would lose the advantages that EF Core brings):

1. If the older code uses (or can be upgraded to use) Entity Framework 6.3.3 or later, then as an initial step you can keep the entity framework code largely unchanged, and just change the other code to .NET 6 or 7. This is because EF 6.3.3 works with .NET Core (see this article).
2. Once you have got rid of the .net framework code and replaced it with .NET 6 or 7, at a later date you can migrate the code from using Entity Framework to Entity Framework Core.