You can try to do a flush on the engine. Some people use a hose to get good water pressure through the entire engine to try and push debris out. There are also Coolant system additives you can purchase to help flush the system before doing a full coolant change.
Funnily enough, ChrisFix's YouTube videos on the coolant system additive and flush are quick, easy to understand right to the point.
https://www.youtube.com/watch?v=s--5ft5YiHg
https://www.youtube.com/watch?v=g8YZF5cW7-A