Presumably when you say “line in a table”, you are talking about a record?
If that’s the case, then this is not something you can do. Each record in Airtable is treated as a data-point when referencing a table from the chart block. Since Airtable is a database, their proper assumption is that a table represents a data set (or a filtered view within a table), and each record is a data-point within that set.
There may be 3rd party services you could port your data out to that can work with a record (row) as a data set, such as https://public.tableau.com/en-us/s/, but I’m not versed in using those.
