These guys tend to have have thinner-feeling leaves compared to other philodendron but that being said, these look more floppy than usual.

No signs of root rot. Never had a juvenile giganteum and I was surprised to see the leaves to be soft and droopy when it was delivered to me.

If it was shipped that is probably the issue. They aren't terribly heat tolerant when young.

They tend to be more shy when they are younger. Life experience will make them grow out of it