Some ideas . . .
Drive the car a few miles to get the engine oil up to proper operating temperature
Drain the oil into a large and clean tub. If it looks like moccha frappuccino, you’ve pretty much verified coolant has gotten into the crankcase
You could also use a block tester to check if combustion gases have gotten into the coolant. If so, some possibilities are failed head gasket, failed intake manifold gaskets, cracked block