pass 120v through 12v control solenoid
In a relay
a) The current rating depends on the size of the contacts and flexible wires to them.
b) The voltage rating depends on the thickness of the insulation between contacts and casing+coil, and the quality of the build.

'200Amp' sounds like a relay with low voltage high current contacts. Without any further information (what's written on it, photograph, part number, contact voltage rating even), it sounds like like it is not rated for 120v, and you will be putting your safety at risk if you connect that voltage to it.

In a 'low voltage' relay, it is assumed that the applied voltage will be below the 'touch safe' limit of 40/50ish volts, and no attention will have been paid to making the relay safe if high voltages are applied.

Assume that if no voltage is written on it for contact rating, it is not safe above 50v.