How to convert Android class to Singleton object (Kotlin)

Currently, I have a database manager class that handles all operations to the database like this:

class DatabaseManager(val context: Context) {
    private val db = Firebase.firestore
    //Other functions, etc.
}

It makes use of the context passed in by different activities to perform functions to the database. The thing is, every single activity that requires database functions have to instantiate this manager class first, then call the functions. I would like to make use of the Singelton design pattern to make it such that all the activities will only use a single instance of the class. I believe kotlin's objects can do this, however I also need to be able to pass in the context of the activities into this manager class. Any assistance is appreciated, thank you!