80%：
/vendor/mediatek/proprietary/packages/overlay/vendor/FrameworkResOverlay/res/values/config.xml
<resources xmlns:xliff="urn:oasis:names:tc:xliff:document:1.2">
<!-- Whether a software navigation bar should be shown.-->
<bool name="config_showNavigationBar">true</bool>
<!-- Minimum screen brightness setting allowed by power manager.
Set this to 0.0 to allow screen to go to minimal brightness.-->
<item name="config_screenBrightnessSettingMinimumFloat" format="float" type="dimen">0.0</item>
<!-- Maximum screen brightness allowed by the power manager.
Set this to 1.0 for maximum brightness range.-->
<item name="config_screenBrightnessSettingMaximumFloat" format="float" type="dimen">1.0</item>
<!-- Default screen brightness setting set.
Set this to 0.4 for Default brightness Float [0.35 == 80%]-->
<item name="config_screenBrightnessSettingDefaultFloat" format="float" type="dimen">0.35</item>
<!-- default color mode -->
<integer-array name="config_availableColorModes">
<item>-1</item>
</integer-array>
</resources>
100%：
/vendor/mediatek/proprietary/packages/overlay/vendor/FrameworkResOverlay/res/values/config.xml
<resources xmlns:xliff="urn:oasis:names:tc:xliff:document:1.2">
<!-- Whether a software navigation bar should be shown.-->
<bool name="config_showNavigationBar">true</bool>
<!-- Minimum screen brightness setting allowed by power manager.
Set this to 0.0 to allow screen to go to minimal brightness.-->
<item name="config_screenBrightnessSettingMinimumFloat" format="float" type="dimen">0.0</item>
<!-- Maximum screen brightness allowed by the power manager.
Set this to 1.0 for maximum brightness range.-->
<item name="config_screenBrightnessSettingMaximumFloat" format="float" type="dimen">1.0</item>
<!-- Default screen brightness setting set.
Set this to 0.4 for Default brightness Float [0.35 == 80%]-->
<item name="config_screenBrightnessSettingDefaultFloat" format="float" type="dimen">1.0</item>
<!-- default color mode -->
<integer-array name="config_availableColorModes">
<item>-1</item>
</integer-array>
</resources>
framework/base/core/res/res/valus/config.xml 这里面的几个修改没有用的
/vendor/mediatek/proprietary/packages/apps/SettingsProvider/res/values/freeme_defaults.xml修改默认亮度也是没用的