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I think standard supply voltage is 3.3V. If you can go down to 1.8V depends on your models, and on your design. It will be difficult if your N- & PMOS transistors have threshold voltages (VTH0 in the model) in the order of 0.8V or more, but it could work well if these threshold voltages are around 0.5V or below, or, if your PDK provides native (zero- or low-VT) transistors - s. also dick_freebird's comment in this forum.
Main problem will be (enough) headroom (of course).
And it depends on the power consumption of your circuit, more accurately if you can design in moderate or weak inversion instead of strong inversion.
But there are many circuits working with 1.8V supply voltage built with 0.35µm processes. Of course not a big deviation lower than 1.8V will be allowed then.