is there a way to regulate the current that the digital ports on the Arduino Uno put out?
There is no one way to reglate the current but multiple ways, based on your application.
1) For some applications, you can rely on the internal resistance of the mcu output pin: it is simple and can be effective for leds whose forward drop voltage is close to the supply voltage;
2) For small leds, you can use a resistor: simple but less efficient.
3) You can also use other ways, like a jfet, or a dedicated CCS driver, or a current mirror with multiple output legs.
4) There are also dedicated switching mode ccs drivers. they offer flexibility and a wide range of output current / voltage options.
Our led's can only hand up to 3.3 volts and I am unsure how much the ports put out.
You will find that your leds can take far more than 3.3v, especially those high power leds.