Django does not allow collapsible inlines.

To enable collapsible inlines, include the js and css into your admin media for the admin class.

class MyAdmin(admin.ModelAdmin):
    inlines = [inline1, inline2, ...]

    class Media:
        css = {
            'all': [
                "%scss/django_admin_collapsed_inlines.css" % settings.STATIC_URL,
            ]
        }

        js = [
            "%sjs/jQuery.js" % settings.STATIC_URL,
            "%sjs/django_admin_collapsed_inlines.js" % settings.STATIC_URL,
        ]


The above js and css works for both TabularInline and StackedInline.