Normally, if the input file is renamed while an F command is
executing, less will continue to display the contents of the original
file despite its name change. If
--follow-name is specified, during an
F command less will periodically attempt to reopen the file by name.
If the reopen succeeds and the file is a different file from the
original (which means that a new file has been created with the same
name as the original (now renamed) file), less will display the
contents of that new file.
So depending on use case one can use
less --follow-name (and type an uppercase
F when the need arises) or use
less --follow-name +F (to have the
F behavior immediately).
This option could also be put for example in the
LESS environment variable to avoid having to type it each time.
By the way
--follow-name is not specifically about symbolic links, but it applies to a replaced symbolic link pointing to a different file.