It really depends on the company. I’m an immigrant myself - I was on an E3 work visa for six years, then got a green card. For me, workload and expectations weren’t any different to a US citizen, and that’s the case at my employer in general.

I plan projects for and and delegate work to junior employees, and I don’t know or care if they’re on a work visa or not. I’ve been in calibration meetings (to handle ratings and promotions) and the person’s visa status is never discussed.