If you are unable to see Brightness option in your Notifications tab, then you can change it directly from the Settings menu.
Firstly, go to Settings option.
Then, go to Display option.
Here, you will see Brightness option through which you can adjust it according to your need.
Now, there is an option 'Auto Brightness' beside it. As you have said that during night it turns very high. So, to avoid this you must uncheck 'Auto Brightness' option.
Even then, if you are facing this issue, then you must visit your nearby Samsung service center.
Samsung has a good coverage of its service center in almost every cities of India.
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