Don't think Elbaph is that kind of arc to be honest. Feels like another exposition type to me so doubt Luffy's going to be defeating someone "definitively" stronger than Kaido (i.e. Loki in this case). That said, he could be comparable to Kaido.
The Giants are the strongest race in the verse for a reason and him having a so called legendary DF could make him filthy PL-wise.
Taking nothing away from Kaido's impeccable combat prowess, his DF and the dura he got from it was one of the main reasons why he was so OP so Loki's DF hype can't be underestimated. There's also Haki, which I'm really not sure how Oda's gonna handle with the giants coz technically speaking, just going off how old they can get and the fact that the Elbaph is called "War Land" which I think implies that the Giants are always embroiled in battle, their Haki should be off the charts as according to Oda "Haki grows in the heat of battle".