I want to say yes to a degree - “great man theory” hadn’t been codified by the time RotTK was written of course but despite the larger than life figures present in the novel I think it refutes the assumptions that lead to the theory.

We have these legendary figures who are sure their actions are backed by inevitable destiny, or are absolute paragons of heroism etc. Guan Yu, Zhuge Liang, Liu Bei, Cao Cao etc. and each eventually pass into history as the wars continue to their end. Some are lauded for their virtues and their deaths are lamented but it’s never said that this was truly the end of some great era of heroes or some such. The ambitions of humans and the rise and fall of nations continues. It’s there from the beginning, the novel is prefaced with the poem:

On and on the Great River rolls, racing east,

Of proud and gallant heroes its white-tops leave no trace,

As right and wrong, pride and fall turn all at once unreal.

Yet ever the green hills stay

To blaze in the west-waning day.

Fishers and woodmen comb the river isles.

White-crowned, they’ve seen enough of spring and autumn tide

To make good company over the wine jar,

Where many a famed event

Provides their merriment.

As I said it used to make me sad to see all these great larger than life heroes die or stray from heroism, what have you, but it rings more true this way I think. Human lives are ephemeral and time again the “greatest” lives are proven to just be human like any other, fallible and fleeting. Life continues.