Google Docs add-ons script to bold everything.

GoogleDocsBoldAll.gs

/**
 * @OnlyCurrentDoc
 *
 * The above comment directs Apps Script to limit the scope of file
 * access for this add-on. It specifies that this add-on will only
 * attempt to read or modify the files in which the add-on is used,
 * and not all of the user’s files. The authorization request message
 * presented to users will reflect this limited scope.
 */

/**
 * Creates a menu entry in the Google Docs UI when the document is opened.
 * This method is only used by the regular add-on, and is never called by
 * the mobile add-on version.
 *
 * @param {object} e The event parameter for a simple onOpen trigger. To
 * determine which authorization mode (ScriptApp.AuthMode) the trigger is
 * running in, inspect e.authMode.
 */
function onOpen(e) {
    DocumentApp.getUi().createAddonMenu()
        .addItem('Start', 'formatInkVN')
        .addToUi();
}
/**
 * Runs when the add-on is installed.
 * This method is only used by the regular add-on, and is never called by
 * the mobile add-on version.
 *
 * @param {object} e The event parameter for a simple onInstall trigger. To
 * determine which authorization mode (ScriptApp.AuthMode) the trigger is
 * running in, inspect e.authMode. (In practice, onInstall triggers always
 * run in AuthMode.FULL, but onOpen triggers may be AuthMode.LIMITED or
 * AuthMode.NONE.)
 */
function onInstall(e) {
    onOpen(e);
}
function formatInkVN() {
    var body = DocumentApp.getActiveDocument().getBody();

    //all text!
    var text = body.editAsText();

    text.setBold(true);
}