H
I’m comparing it because it’s the same. Characters in this series talk a bunch of shit. A lot of the time, they don’t back it up or it’s a bluff. It literally happened to Luffy earlier in the arc, the first time he tried to fight Kaido. Zoro has been victim of it in the past, when he challenged Mihawk and got destroyed with a butter knife. It happens all the time.
Let me run this by briefly...
Zoro in 989, wanting to join Luffy to fight Kaido


Zoro in 997; after seeing Kiku’s severed arm falling from the rooftop, finally gets fed up with the “games” in the balcony and makes his proclamation. Then even goes on to say he wants to go up there once again:

Once is chance
Twice is coincidence
Three times is a pattern.
And then you got this statement from Kaido after the Scabbards failed in their attempt to cut him down;

After all the sword that mortally wounded him and was untouched for decades, a sword whom even the Scabbards dared not to tame is now wielded by Zoro
And then you got the legend of Ryuma cutting a Dragon “above the capital”

Zoro draws obvious parallels to Ryuma and now the stage for the final fight is looking the capital of Wano, once again pointing towards an obvious direction.
I can go on but I think any sensible reader gets the point already, how is this in any way a bluff?
To call all this a bluff or compare it to some off hand comment made by Sanji for which the purpose of was to handle an imminent danger to his crew is absolutely ludicrous.
Like you either gotta be not reading some parts of Wano or you are just in complete denial of what’s to come with Zoro.