Can you extend the record type similar to an extension method?

Lets say as it happens to be the case, that all my models/poco's are records. It just so happens we find it useful in many cases to convert our models to json. So that we don't have to override the .ToString() in every model an entitybase record was created with the following method and inherited by the rest of the models:

public record EntityBase
{
    public override string ToString()
    {
        return System.Text.Json.JsonSerializer.Serialize(this);
    }
}

But I wondered if there were a way to modify or extend the record or class type almost similar to an extension method.

    // record / class are not valid types here
    public static string ToString(this record value)
        => System.Text.Json.JsonSerializer.Serialize(value);
    
    // this works but I want to constrain it to records and non generic methods do not allow constraints
    public static string ToString(this object value)
        => System.Text.Json.JsonSerializer.Serialize(value);

I can think of a million reasons it might be a bad idea but I am curious if it possible? Is there another or better way to modify these types if its possible?

Per the documentation:

> There's no generic constraint that requires a type to be a record. Records satisfy either the class or struct constraint. To make a constraint on a specific hierarchy of record types, put the constraint on the base record as you would a base class.

So you could define an abstract base entity:

public abstract record BaseEntity();

Derive all your records from it:

public record MyEntity(...) : BaseEntity();

Then define your extension method this way:

public static ToJson<T>(this T source) where T : BaseEntity
{
    return System.Text.Json.JsonSerializer.Serialize(source);
}

But of course if you're going to do that, you may as well put it in BaseEntity.

public abstract record BaseEntity()
{
    public override string ToString() => System.Text.Json.JsonSerializer.Serialize(this);
}