To be sure, you'd need to:
* Find the specifications for the Chrysler 300 wheels: This includes the bolt pattern (e.g., 5x114.3mm or 5x4.5 inches), wheel offset, and hub bore diameter. You can usually find this information on the wheel itself (often cast into the metal), in the owner's manual for the Chrysler 300, or online with the wheel's part number.
* Find the specifications for the 1998 Cadillac DeVille's wheel hubs: Do the same as above for your Cadillac. You can find this information online or in a Cadillac parts catalog.
Only if all three specifications (bolt pattern, offset, and hub bore) match exactly will the wheels fit. Even then, there's a possibility of clearance issues with the brakes or suspension components.
It's highly recommended to consult a tire and wheel specialist or use a wheel compatibility checker online (many exist) before attempting to install wheels from one car onto another. Using incompatible wheels can be dangerous and may damage your car.