android_device_xiaomi_sm8450-common/overlay/FrameworksResXiaomi/res/values/config.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
     Copyright (C) 2024 The LineageOS Project
     SPDX-License-Identifier: Apache-2.0
-->
<resources xmlns:xliff="urn:oasis:names:tc:xliff:document:1.2">
    <!-- Minimum screen brightness setting allowed by power manager.
         -2 is invalid so setting will resort to int value specified above.
         Set this to 0.0 to allow screen to go to minimal brightness.
         The user is forbidden from setting the brightness below this level. -->
    <item format="float" name="config_screenBrightnessSettingMinimumFloat" type="dimen">0</item>

    <!-- Maximum screen brightness allowed by the power manager.
         -2 is invalid so setting will resort to int value specified above.
         Set this to 1.0 for maximum brightness range.
         The user is forbidden from setting the brightness above this level. -->
    <item format="float" name="config_screenBrightnessSettingMaximumFloat" type="dimen">1</item>

    <!-- Default screen brightness setting set.
         -2 is invalid so setting will resort to int value specified above.
         Must be in the range specified by minimum and maximum. -->
    <item format="float" name="config_screenBrightnessSettingDefaultFloat" type="dimen">0.5</item>
</resources>