From my experience, the Grammarly Chrome extension can help you build confidence in your writing skills. Also, I now sometimes use chatGPT to rewrite texts for external presentations, etc.
Overall, reading professional articles and watching online courses help you expand your active vocabulary and boost your confidence.
Yep, watching foreign movies and TV shows with subtitles is a great way to immerse yourself in the language. Podcasts and music help too - anything that gets your ear accustomed to the sounds and rhythms. Getting out there and speaking with native speakers as much as possible is key though!