Is there a way to alter the 5V 2A wall wart into 5V 5A? I want to power neopixel LEDs but I just need slightly more current supply.
Converting voltages and currents requires the total maximum power to not increase. In other words, input V * I >= output V * I (this is the concept of conservation of power). Therefore, it would be impossible to convert a 5V * 2A = 10W input to a 5V * 5A = 25W output because the 10W input is not greater than the 25W output.
Is there a way to alter the 5V 2A wall wart into 5V 5A?
No. Not gonna happen. Fahgeddaboudit.
I just need slightly more current
A factor of 2.5 is a lot more than "slightly" higher.
If the 2 A wall wart could produce 5 A, then it would be sold as such and therefore fetch a higher price. The manufacturer had to pick something as the spec, and they picked 2 A.
These things are manufactured in high volume, so saving parts cost probably got significant design attention. Parts to support 5 A output would definitely cost more, and would take more space and weigh more too. You can't just tweak a resistor somewhere and have the device output 2.5 times more power.
If you want 5 V at 5 A, go buy a 5 V 5 A wall wart or power supply. These things are quite cheap nowadays. You can buy a ready-made unit for less than you can buy the parts for separately in low volumes.
What you are asking to do just doesn't make sense. Not even close.