In informal writing multiple question marks can be used to express excitement or increased confusion about something (it depends on the context). In more formal writing and fiction writing you wouldn’t expect to see multiple question marks in a row unless the writer was trying to show a text message that a character received from a friend for example. Here is how multiple question marks would work if you were messaging a friend:

You’re expecting a baby????? Congratulations! – this indicates that you’re excited by the news but you’re asking to make sure. Again, multiple question marks should only really be used in informal circumstances.