Django: How to display a pdf file in a new tab?

Most of the posts showing how to open a pdf file in a new tab are 3 years old. What is the best way in Django to open a pdf file uploaded to a model?

invoice.py

class Invoice(models.Model):    file = models.FileField(upload_to='estimates/', blank =True)    name = models.CharField(max_length=250, blank =True)        def __str__(self):        return self.name

views.py

def view_invoice(request, invoice_id):    invoice = get_object_or_404(Invoice, pk=invoice_id)    return render(request, 'index_invoice.html', {'invoice': invoice}) 

index_invoice.html

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Many Thanks