$post = new Post([
'title' => 'Batatas não avoam',
'author' => 'Lucas Pires',
]);
$post->save();
$post = Post::find($id);
$post->title = 'Novo titulo';
$post->save();
$post = Post::find($id);
$post->fill($request->all());
$post->save();
ou
Post::find($id)->fill($request->except('_token'))->save();