connect heater ac 220v 1200W to arduino

please , anyone help me
i want to connect heater ac 220v 1200W to arduino to change voltage ac for change temperature of heater
anyone could tell me how can i do it? , can i use moc3021 IC to do it?
please ,any schematic diagram or draw shown it.

I would use a SSR-25DA or similar solid state relay.

Indeed, switch an SSR relay say, 30 seconds on, 30 seconds off, and you'll get temperature control.
Look into how much current the MOC3021 supports and see if you can see why you would not use it in this application.

To do proper "voltage variation" of an AC signal you have to chop the waveform up, which at high currents takes speciality hardware and components. Yes, it is possible, but the cost and complexity of the design is not worth it for this application.

Heater elements are very slow (on the scale of things) to respond to changes in their power supplies. They take time to heat up, and they hold their heat for some considerable time afterwards.

As a result it is much better, cheaper, and simpler, to use just switch the heater on and off over much longer periods (30 seconds has been mentioned before). Adding some temperature feedback (say a thermocouple) makes it even better, as you then know what temperature the heater is at. This is basically how your kitchen oven works - turn on the heaters until it reaches a preset temperature, then turn off. When the temperature falls too low turn the heaters back on again. Repeat.

You can then do the switching with a simple SCR or even a mechanical relay.