Coup follower, perhaps

• Unveiling shout
• "Et voilà!"
• Cry made with a curtsy, maybe
• Flourish sound
• Exclamation with a dramatic reveal
• Drumroll follower, at times
• "And boom goes the dynamite!"
• "Did it!"
• "... and here it is!"

Wiktionary Word definitions in Wiktionary
interj. (alternative spelling of ta-da English)