Full disclosure, I'm still a student in college studying audio visual, mainly as an audio guy. I'm working towards becoming a composer, sound designer, boom op, and film mixer for media; I've been able to work in the school's studios for about 8 months now. Since we're a broadcast studio mainly and regularly post videos and other content online and on streaming platforms, we usually aim for -24 LUFS which is broadcast standard (may fluctuate a dB or two depending on what scale you use for your country's regulations).
-24 LUFS is easy enough for mono/stereo signals but for surround it becomes trickier for loudness as each monitor could output varying levels depending on how you had your guys mix it. There's a really good article here you can read that goes into way more depth and from much more reliable, experienced sources:
https://www.pro-tools-expert.com/home-page/2017/6/21/loudness-and-dynamics-in-cinema-sound
Short answer: Something every sound guy should learn early on is that it's never ok to slam any mix into limiters for loudness. Do what's best for the film's dynamic range and what you have for your vision. Don't be afraid to take charge of your projects, especially with sound. I've worked with a good handful of people since I started college, some directors and producers who take charge and others who I rarely hear from unless it's a mix review. It'd be good to learn about audio loudness standards and communicate that with your sound department clearly, and don't be afraid to tell them to turn it down.
If you're working audio for screenings it's even more important, I think, to learn about loudness standards and oversee the sound guys you work with as much as you can. We all love to hear good sound but moderation in everything does our ear's justice
