Yes, it is. 'The Watcher' is based on a true story that happened in Westfield, New Jersey. A family bought a house and then started receiving creepy letters from someone calling themselves 'The Watcher'. It made their living situation a nightmare.
The Jack Ryan series incorporates aspects of truth, but it's not a pure account of real happenings. It weaves in fictional elements to make the story more thrilling and accessible to a wide audience.
It has some basis in real events and situations, but it's not a completely accurate retelling. The creators have mixed fact and fiction to make it more engaging for the audience.