A bad head gasket can cause an engine to burn oil.
The head gasket seals the engines coolant and oil passages from the engines cylinders and when the head gasket fails it can cause engine oil to get into the engine cylinders which can cause the engine to burn off the engine oil.
A bad head gasket can also cause coolant to be burnt and cause coolant to get into the oil as well.
If your engine is not getting coolant in the oil then it could be the valve seals causing the engine to burn oil or you have bad piston rings.
But it can also be a bad head gasket.
Replacing a head gasket is a major job because it requires removing the engine heads and putting new bolts in and then putting all the parts back together.
If you don't know how to replace the head gasket then it's best to have a shop do it because the engine head bolts need to be torqued down in the proper sequence and torqued down to specs.
If your head gasket is not majorly blown then using a bottle of block seal from Bar's can work to stop the head gasket leak if it's in the coolant passages.
But if it's an oil passage then the head gasket block seal in a bottle will not work.