A LED is a current controlled device each white LED is around 3 volt. So having a current controller called a driver one is normally limited to 48 volt so 3 into 48 equals 16 LED's from one driver.
Where the driver and LED's are combined as a package then often one needs a set voltage rather than current.
Unfortunately lighting manufacturers seem to set out to confuse people and call some constant voltage power supplies drivers as well as the constant current ones. So one has to read the spec very carefully.
Constant current is very good for long runs as all lights at same brightness. This is actually used with run way lighting transformers for each lamp are wired in series not parallel like most lamps.
So your question is down to package bought. You may be able to cut and extend but it is not a one size fits all and it depends on what you buy. Some can be cut some can't.
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