If you try to draw 3.6 A from a laptop USB port, what happens depends on the design of the electronics powering the USB port.
The USB port:
- might just support 3.6 A (not very likely)
- does not support 3.6 A and will deliver a certain maximum current and might shut down immediately or after a while (most likely)
- it might break if it is poorly designed (not that likely)
What happens when powering from an Arduino is similar, it depends on the design of the Arduino but also how you power the Arduino.
If you power the Arduino from 5 V then that power supply might limit the current. If there is a (resettable) fuse in the 5 V line of the Arduino it might blow (or go open if it is resettable).
If you feed the Arduino via Vraw an internal regulator is used to regulate this voltage down to 5 V. This regulator cannot support that much current so you will not get 5 V out of the Arduino for a long time. When the regulator heats up too much it might shut down.
In general: you simply should not power a device which needs 3.6 A from anything that cannot supply at least 3.6 A. Especially "dumb" loads like LED strips which aren't "intelligent" in the sense that they will draw less current when a high current cannot be supplied. Some smartphones are "intelligent" and adapt their power consumption to the source used.