Hi
Unfortunately you will need to replace the display assembly as it’s the easiest option and for most people the only option unless you have the equipment to separate the glass and display
Here’s the guide to replace the display
[guide|143953|new_window=true]
This guide isn’t fully finished but it should get you though the majority of it
If you could find a screen protector or privacy screen for your iMacs display it could help make the crack less noticeable
Hopefully this helps
Any questions please ask
Thanks:-)