According to my requirements, I need to add new line type (Like Item,resource,comment etc are already existing.), but there is no option to add new line type. Is there any way to add new line type. I can use AL extension too if there is any way.
There is currently no way to extend an option field with a new option via an AL Extension.
But it's a much requested feature and I'm sure Microsoft is working on it, which of course doesn't help you now.
If your question were NOT about Business Central, then as any other field it can be changed in C/SIDE.