Is it permissible to work as a software developer for companies that add visual effects (VFX) to cinematic works and advertisements, knowing that the nature of the work is limited to producing and modifying software?

There is no objection to working on the production and development of software if the company's primary activity is its use in permissible matters. However, if the company's primary activity is the use of software in forbidden things, such as films and sinful advertisements, then it is not permissible to work on producing and developing software for it, due to the Almighty's saying: "And do not cooperate in sin and aggression. And fear Allah; indeed, Allah is severe in penalty."