It depends on how much of the work you’re doing. For all the visuals aspects you can use just Blender.
You can use blender’s text editor for handling scripts for narrator and/or voice actors. I do this and use the Fountain.io markdown format. Then I use a downloaded version of afterwriting.com to convert fountain to a screenplay PDF for the actors to use. I also use Libre Office as my office suite. You can use write or MS Word for writing your script. Fountain works as long as you can save it as a plain text format
You will also need Audio software for sound recording and editing. Blender can handle some of the sound design aspects, but not sound editing and recording. I use Audacity as my DAW and musescore for MIDI and sound FX. I have recently started using Davinci Resolve for ADR (recording voice actors) and sound editing/design. I also use it for color correction and advanced video editing/visual effects work.(I’m still learning it)
It’s a good idea to have additional tools for texture creation and image manipulation. I currently use Gimp and have started learning Krita. A lot of people use substance painter for quicker texturing.
