finally I find this modification can print multiple font size

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WebSettings wSettings = myWebView.getSettings();
String st = editText2.getText().toString();
st = st.replaceAll("\n", "<br>");
myWebView.loadDataWithBaseURL("file:///android_asset/", st, "text/html", "UTF-8", null);
wSettings.setTextZoom((int)(editText2.getTextSize()*2));//You can change 2 to the multiple you want
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