Carriage return in Field Title

Is it possible to insert a line break in the field: Title ?

I do not think it is possible to enter an actual line break in the field Title.
The main reason is that JabRef files are, by default, designed to be used by bib(la)tex, and it is bib(la)tex’s job to break the lines.
Maybe inserting a command \newline (or \protect\newline) in the title field may affect bib(la)tex behavior (I have not tested).

Where does your need to insert a line break in the title come from?

Thank you for the reply. LaTeX commands \newline or \protect\newline does not work.
The reason I ask about this is that the original paper headlines are often a) long and/or b) already contain a line break. And better readability.

Well, if you are using bib(la)tex, the line breaks will be taken care by bib(la)tex directly, even for long titles. And for a line break in the original title, this is not usually considered as mandatory to reproduce in a bibliographic list.
About better readability: in which document/software? The preview panel of JabRef maybe?