Can PCI-E x16 (2.0) power a Radeon RX550

It varies with the size of the case. Which 3010 do you have?
PCIe 2.0 isn't an issue. There are no GPUs that need more bandwidth than PCIe 16x 2.0 provides. Even the fastest ones only lose a few percent performance running at PCIe 2.0 8x.
Dell usually prints any power limitations right on the motherboard next to the PCI-e slot, for example if it says "25w" there then that ~50w card will not work.

I do not see any such text on the 3010 motherboards in Google Image Search so it should be able to supply the whole 75w.