If this specific sound isn't perfect, you can find similar audio at these sources:
ElevenLabs Free Countdown Sound Effects : AI-generated options like chimes and ticks. If you can tell me: Download countdown boom 76577 mp3
For maximum impact, layer this sound effect with a low-frequency rumble or a slight crescendo (gradual increase in volume) during the countdown numbers leading up to the boom. If this specific sound isn't perfect, you can
The sound effect "Countdown-Boom" (specifically ID 76577, often credited to Russintheus) is a popular, dramatic cinematic effect. You can download it for free from Pixabay . Format: MP3 Source: Pixabay License: Free for use under the Pixabay Content License. You can download it for free from Pixabay
Mixkit Countdown Sound Effects : Various styles, including clock bleeps and voices.
Use software like Audacity to increase the bass if the boom needs to sound more cinematic.