Nope. We see a full picture of Pica's upper body, where he is clenching his fist right next to his face.
Still depends on how large Pica's palm is compared to his torso. I mean isn't it clear that Pica's arms are disproportionally large?
So if you want a correct perspective, you need to have Hajrudin sitting right on Pica's head.
Here we have a direct comparison of Luffy's Grizzly Magnum to Pica's face:
So how large is G3? Arguably as large if not a bit smaller than Chinjao in height:
And Hajrudin is 4 times as large as Chinjao, as Chinjao has a confirmed height of 5 meters.
So Hajrudin has arguably the size of Pica's head if not taller.
So yeah, just posting a close up of Pica's palm to prove that he cannot be "mere" 300-400m is just as baloney.