Should we declare mongoose schema in database connection script?

async function updateProfilePicture(newFileName) {
    await connectDB();
    try {

        const userSchema = new mongoose.Schema({
          name: String,
          profilePic: String
          });
        const User = mongoose.model('User', userSchema,'users');
        const res = await User.updateOne({name:"John"},{profilePic:`${newFileName}`})
        console.log(res);

        console.log("Updated");
    } catch (error) {
        console.error(error.message);
        throw error;
    }
}