这里主要需要注意2个文件。InvariantDeviceProfile和device_profiles.xml。

//packages\apps\Launcher3\src\com\android\launcher3\InvariantDeviceProfile.java
InvariantDeviceProfile(Context context) {
....
        InvariantDeviceProfile closestProfile = closestProfiles.get(0);
Log.d("DeviceProfile", "DeviceProfile name = " + closestProfile.name);
....
}

打印出当前使用的Profile的name。结果显示是 Stubby。
修改前device_profiles.xml如下所示。

<profiles xmlns:launcher="http://schemas.android.com/apk/res-auto/com.android.launcher3" >

    <profile
        launcher:name="Super Short Stubby"
        launcher:minWidthDps="255"
        launcher:minHeightDps="300"
        launcher:numRows="2"
        launcher:numColumns="3"
        launcher:numFolderRows="2"
        launcher:numFolderColumns="3"
        launcher:minAllAppsPredictionColumns="3"
        launcher:iconSize="48"
        launcher:iconTextSize="13.0"
        launcher:numHotseatIcons="3"
        launcher:defaultLayoutId="@xml/default_workspace_3x3"
        />

    <profile
        launcher:name="Shorter Stubby"
        launcher:minWidthDps="255"
        launcher:minHeightDps="400"
        launcher:numRows="3"
        launcher:numColumns="3"
        launcher:numFolderRows="3"
        launcher:numFolderColumns="3"
        launcher:minAllAppsPredictionColumns="3"
        launcher:iconSize="48"
        launcher:iconTextSize="13.0"
        launcher:numHotseatIcons="3"
        launcher:defaultLayoutId="@xml/default_workspace_3x3"
        />

    <profile
        launcher:name="Short Stubby"
        launcher:minWidthDps="275"
        launcher:minHeightDps="420"
        launcher:numRows="3"
        launcher:numColumns="4"
        launcher:numFolderRows="3"
        launcher:numFolderColumns="4"
        launcher:minAllAppsPredictionColumns="4"
        launcher:iconSize="48"
        launcher:iconTextSize="13.0"
        launcher:numHotseatIcons="5"
        launcher:defaultLayoutId="@xml/default_workspace_4x4"
        />

    <profile
        launcher:name="Stubby"
        launcher:minWidthDps="255"
        launcher:minHeightDps="450"
        launcher:numRows="3"
        launcher:numColumns="4"
        launcher:numFolderRows="3"
        launcher:numFolderColumns="4"
        launcher:minAllAppsPredictionColumns="4"
        launcher:iconSize="48"
        launcher:iconTextSize="13.0"
        launcher:numHotseatIcons="5"
        launcher:defaultLayoutId="@xml/default_workspace_4x4"
        />

    <profile
        launcher:name="Nexus S"
        launcher:minWidthDps="296"
        launcher:minHeightDps="491.33"
        launcher:numRows="4"
        launcher:numColumns="4"
        launcher:numFolderRows="4"
        launcher:numFolderColumns="4"
        launcher:minAllAppsPredictionColumns="4"
        launcher:iconSize="48"
        launcher:iconTextSize="13.0"
        launcher:numHotseatIcons="5"
        launcher:defaultLayoutId="@xml/default_workspace_4x4"
        />

    <profile
        launcher:name="Nexus 4"
        launcher:minWidthDps="359"
        launcher:minHeightDps="567"
        launcher:numRows="4"
        launcher:numColumns="4"
        launcher:numFolderRows="4"
        launcher:numFolderColumns="4"
        launcher:minAllAppsPredictionColumns="4"
        launcher:iconSize="54"
        launcher:iconTextSize="13.0"
        launcher:numHotseatIcons="5"
        launcher:defaultLayoutId="@xml/default_workspace_4x4"
        />

    <profile
        launcher:name="Nexus 5"
        launcher:minWidthDps="335"
        launcher:minHeightDps="567"
        launcher:numRows="4"
        launcher:numColumns="4"
        launcher:numFolderRows="4"
        launcher:numFolderColumns="4"
        launcher:minAllAppsPredictionColumns="4"
        launcher:iconSize="54"
        launcher:iconTextSize="13.0"
        launcher:numHotseatIcons="5"
        launcher:defaultLayoutId="@xml/default_workspace_4x4"
        />

   
    <profile
        launcher:name="Nexus 7"
        launcher:minWidthDps="575"
        launcher:minHeightDps="904"
        launcher:numRows="5"
        launcher:numColumns="6"
        launcher:numFolderRows="4"
        launcher:numFolderColumns="5"
        launcher:minAllAppsPredictionColumns="4"
        launcher:iconSize="64"
        launcher:iconTextSize="14.4"
        launcher:numHotseatIcons="7"
        launcher:defaultLayoutId="@xml/default_workspace_5x6"
        />

    <profile
        launcher:name="Nexus 10"
        launcher:minWidthDps="727"
        launcher:minHeightDps="1207"
        launcher:numRows="5"
        launcher:numColumns="6"
        launcher:numFolderRows="4"
        launcher:numFolderColumns="5"
        launcher:minAllAppsPredictionColumns="4"
        launcher:iconSize="76"
        launcher:iconTextSize="14.4"
        launcher:numHotseatIcons="7"
        launcher:defaultLayoutId="@xml/default_workspace_5x6"
        />

</profiles>

由于当前使用的是 Stubby，那么修改 launcher:name="Stubby"所对应的profile即可。将launcher:iconSize="48"修改为launcher:iconSize="70"。

<profile
        launcher:name="Stubby"
        launcher:minWidthDps="255"
        launcher:minHeightDps="450"
        launcher:numRows="3"
        launcher:numColumns="4"
        launcher:numFolderRows="3"
        launcher:numFolderColumns="4"
        launcher:minAllAppsPredictionColumns="4"
        launcher:iconSize="70"
        launcher:iconTextSize="13.0"
        launcher:numHotseatIcons="5"
        launcher:defaultLayoutId="@xml/default_workspace_4x4"
        />

参考链接：
Launcher3布局的布局配置
Android系统的桌面图标文字——调整字体大小、图标和文字间的间隔
【Launcher开发】Android桌面布局分析