I need convert unreal engine 4.6 to unreal 5 blueprint and everything in this level
If it was me I would download stepping stone versions of the engine > large changes have been made over the years > this will be a long process but will be the safest > you could get every version between 4.6 and 5 but that seems like over kill > I would look for major engine changes in the change lists > then move the entire project to that incremental version (test it to make sure it works) Fix all the issue > then move along to the next version > I would try to skip as many as possible until I got to 4.27.3 then it should be ok. You will also have to disable all plugins that are not supported by epic and or recompile them if you can’t do this you might want to remove that content and plugin early on so you will avoid issues.
I try to not let a project get this out of date and upgrade them leaving an old copy for around a year in the launcher after backing up it up before I do the conversion. I have been using this method since 4.7 when I started using UE4.
If you are doing this as a contractor make sure you document all the work it takes to do it as they might struggle to realize how complicated this can be.