In D8, where to change the Public File System Path to be :
sites/default/files/[nodeID]/
Do I need write a module?
You can't change the public file system path globally to include a nodeID
because there are things that can store files that do not have a nodeID
(such as non-node entities).
Instead, you can change where files are stored per file storage field (examples: File fields and Image fields).
To do so, go to Structure -> Content Types -> My Content Type -> Manage Fields
and then choose Edit for the relevant field.
Then, in File directory, you can use tokens to set up the path however you like. For example:
myfiles/[date:custom:Y]-[date:custom:m]-[date:custom:d]
There is a link below Help text that you can click to see a list of available tokens.