So on Instagram, a dark fashion came out. I looked at how to activate it and there I have to activate the dark mode.
I've activated this on my Huawei P20 Pro, but Instagram is still bright.
You can install the app "DarkMode" in PlayStore. Once you have the app you just have to open it. The rest is self-explanatory.
Through this app, all apps that are able to activate the night mode are affected.