This chapter implied one thing: The temperature/heat of Sanji's "passion" burns very high. In Ennies Lobby he could have turned up the heat, but his body couldn't take it. So he can turn up the "oven" as high as he wants to and is only limited by his durability.
Let's not forget this is Sanji's first major 1 v. 1 since Jabra, where he invented Diable Jambe. But Diable Jambe was invented when he couldn't even use basic Haki.
Now post-TS with the "exoskeleton" and the "CoA [he's] been training" he can turn up the heat much higher.
So Sanji could ALWAYS turn up the heat (his passion is limitless), even in Ennies Lobby. But he was limited by his durability of the time.
The higher his durability = The hotter his flames
Let's not forget this is Sanji's first major 1 v. 1 since Jabra, where he invented Diable Jambe. But Diable Jambe was invented when he couldn't even use basic Haki.
Now post-TS with the "exoskeleton" and the "CoA [he's] been training" he can turn up the heat much higher.
So Sanji could ALWAYS turn up the heat (his passion is limitless), even in Ennies Lobby. But he was limited by his durability of the time.
The higher his durability = The hotter his flames