If the Samsung Galaxy A13 brightness for the screen is not high, even at maximum settings, here are some potential solutions:
Increase Brightness Manually
Head to Settings > Display > Brightness and bump it up all the way.
If it is enabled, turn off Adaptive Brightness.
Turn Off Power Saving Mode
Go to: Settings > Battery and Device Care > Battery > Power Saving Mode
Disable it if the option is turned on because it lowers the brightness level of the screen.
If Possible, See if You Can Turn Off the Blue Light or the Extra Dim Mode
ж Settings > Display > Eye Comfort Shield