John K has already provided an example of what a sonic boom feels like from very close, and Harper - Reinstate Monica describes it in general terms. Let me give you a practical example of what a sonic boom did in a radius of 100 km.
On 22 March 2018, Air France flight AF671A from Réunion to Paris Orly was flying over northern Italy when it lost radio contact with Air Traffic Control. Two Eurofighter Typhoons were sent to investigate, and as they rushed there they broke the sound barrier.
The sonic booms were heard from Aosta to Bergamo, which are 180 km apart. And at first they were mistaken for bombs. The result? Among other things, there were hundreds of calls to the police, people ran out of buildings in panic, some schools and offices were evacuated, and some windows got broken.
And at an airshow they'd fly much lower, so it would be louder!
To be fair, it was explained that the wind and weather conditions were unfortunate, as they favoured the propagation of sound, but in any case a sonic boom is way too loud to be done for fun: it's only allowed in case of emergencies.
By the way, in the end it turned out it was a false alarm, so at least there was a happy ending.
[Sources: in English, in Italian]