Instead of belongsTo, use hasMany

For belongsTo relationship, instead of passing parent's ID when creating child record, use hasMany relationship to make a shorter sentence.

// if Post -> belongsTo(User), and User -> hasMany(Post)...
// Then instead of passing user_id...
Post::create([
    'user_id' => auth()->id(),
    'title' => request()->input('title'),
    'post_text' => request()->input('post_text'),
]);
 
// Do this
auth()->user()->posts()->create([
    'title' => request()->input('title'),
    'post_text' => request()->input('post_text'),
]);