What connectors should I use with 5V DC current?
Crimped electrical terminals that you find at the hardware store are the simplest and most available high-current connectors that requires the cheapest and least amount of tools for most people. These include the ring, spade/forked connectors that  get screwed down.

The hardware store also has similarly crimped Quick-Connect connectors that have a male and female end that you can plug into each other wire-to-wire. The female terminal is often just sitting inthe hardware store, however the male end is less common to find sitting in a hardware store, so you may have to order online.

The easiest thing is just to google an ampacity table and look up the AWG for current unless you want to do super-physics calculations and simulations for wire heating. Rule of thumb: if the wire fits in to the connector then the connector can probably support at least as much current as the wire can. There's little point to making a connector that can fit a 12AWG wire but can't carry the current of a 12AWG wire. Usually the limiting factor is the insulation or plastic on the connector or wire since that will melt/burn long before the metal conductor does.

Voltage and current ratings are independent. You can't trade one for the other.