The first thing to know is that it depends on where the tyre is punctured.
In the tread area :
The tyre is repairable in most cases. Unless the puncture is too large, tyre repair is usually possible. However, it is important to remove the tyre to ensure that it is not marbled and/or damaged by driving at low pressure.
In the shoulder area :
A tyre puncture repair in this area is not possible. The tyre must be replaced.
In the sidewall :
he tyre is generally not repairable, there is a high risk that the puncture has damaged and weakened the overall structure.
There is one exception:
If the speed rating on the sidewall of your tyre does not exceed the T rating, the sidewall is repairable if the hole is 3mm or less in diameter. Beyond this index, tyre repair is strongly disadvised to avoid any safety risk.