What happens when the resistance is 0? If the resistance in the circuit is a few ohm, according to Ohm's law, will the current increase?

What happens when the resistance is 0? If the resistance in the circuit is a few ohm, according to Ohm's law, will the current increase?

Not necessarily
You said that according to Ohm's law
If the voltage is 0.00x V, the current is still very small
But you can say that
When the resistance approaches infinity, the current will be very large
But this is basically the legendary short circuit of the power, do not advocate, there is danger

How to get 0.3 ohm resistance

The wire itself has resistance; different materials, different cross sections, the resistance value is different. You choose the wire with 0.3 ohm resistance value!