Is this an efficient nosql database design idea if I am storing an unbounded array of references in a document?

Question

I am learning nosql database design by developing a nodejs backend for a social network type application.

User schema in my backend is this:

userSchema = new mongoose.Schema({
    name: {
        type: String,
        required: true
    },
    email: {
        type: String,
        required: true
    },
    hashed_password: {
        type: String,
        required: true
    },
    isVerified: {
        type:Boolean,
        default: false
    },
    emailVerificationToken: String,
    emailVerificationTokenExpires: Date,
    followers: [{ type: ObjectId, ref: 'User'}],
    following: [{ type: ObjectId, ref: 'User'}],
    pins: [{type: ObjectId, ref: 'Pin'}],
    bio: String,
    website: String
});

I am storing an array of references to followers which is an unbounded array. I know that the maximum document size is 16 MB. I want to develop a backend which must be scalable to handle millions of users. Should I have a separate schema to store followers, following data or the current database design is fine?