I suggest to add the link “https://help.libreoffice.org/6.4/en-GB/text/scalc/guide/cellreferences.html” for more helpful information around the topic “Referencing other sheets” to the documentation “To specify a data range”. https://help.libreoffice.org/6.4/en-GB/text/schart/01/wiz_data_range.html#hd_id1877193
Changing component to Documentation
Please explain the steps you want to achieve. It appears not possible to have a data range directly from another file, except by pasting the data into cells in the file that holds the chart.
(In reply to Olivier Hallot from comment #2) I would appreciate helpful descriptions for functionality which is partly explained by an information source like the following. Support for referring to tables from external files https://bugs.documentfoundation.org/show_bug.cgi?id=122011#c11