I've done it. The larger the grid, the more difficult it is. But as long as you have fuel and an adequately maintained grid, its not as hard as some in the comments make it out to be. Better regulation would make it easier. For instance, in Singapore emergency diesel or some other method for black start is a requirement for most generation stations. The rest of the world likely has more lax requirements.
I’ve done small systems less than 2 MW with 2-3 generators, a mix of hydro and diesel, and only distribution level voltages.
It seems like you would black start some plant using its backup diesel generator to power pumps and controls, probably synchronize at least two units at the plant, then pick up some part of the transmission system. Perhaps the capacitance of the grid is and issue when it is unloaded, so the trick is to make sure enough real and reactive capacity is online for each subsequent transmission or load step. Probably a lot of transmission steps come with a significant amount of load too - not just picking up unloaded transmission lines. Sounds really fun, banging all the governors and exciters with once in a decade load steps
There is also the new distributed restart plan: https://www.neso.energy/about/our-projects/distributed-resta...