InvalidArgumentException The "" file does not exist or is not readable.

hello, i am trying to upload pdf file path in database using laravel. there is a problem. if a file size greater than 1.5MB, this error occurred. according to my project feature, user can upload a very big file like 100MB pdf file! so how can i resolve it? Note: i am using linux. and working on local host.

here is view form -

@section('content')
<div class="container">
        	<form action ="{{ route('posts.store') }}" enctype="multipart/form-data" method="post">
            @csrf
        	<div class = "row pt-3 pb-3">
        		<h2>Add new post</h2>
        	</div>
                          <div class="row">
                          	<div class = "col-11 offset-1">

                            <div class="form-group row">
                            <label for="pcaption"
                             class="col-md-1 col-form-label ">
                             post caption
                            </label>

                            <div class="col-md-8">
                                <input id="pcaption"
                                 type="text"
                                 class="form-control @error('pcaption') is-invalid @enderror"
                                 name="pcaption"
                                 value="{{ old('pcaption') }}"
                                 required autocomplete="post caption"
                                 autofocus>

                                @error('pcaption')
                                    <span class="invalid-feedback" role="alert">
                                        <strong>{{ $message }}</strong>
                                    </span>
                                @enderror
                            </div>
                        </div>

<div class = "row">

      <input id = "post"
       type = "file"
       class = "form-control-file pt-2 pl-6"
       name  = "post">
      @error('post')
       <span class="invalid-feedback" role="alert">
       <strong>{{ $message }}</strong>
       </span>
      @enderror
    </div>

<div class="row pt-4">
	<button class="submit col-md-1">upload</button>
	<button class="btn btn-danger col-md-1 offset-md-5">cancel</button>
</div>
</div>
 </div>


        		</form>
            </div>
            @endsection

here is modal code -

namespace App;

use Illuminate\Database\Eloquent\Model;

class post extends Model
{
	protected $guarded = [];

    public function user()
    {
    return $this->belongsTo(User::class);
    }

}

here is my controller code -

namespace App\Http\Controllers;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\Auth;
use Illuminate\Support\Facades\DB;

class PostsController extends Controller
{
  
  public function create()
    {
        $id = Auth::id();
        $user = DB::table('users')->find($id);
        return view('posts', ['user' => $user]);
    }
    public function __construct()
    {
    	$this->middleware('auth');
    }
    public function store()
    {

    	$data = request()->validate(['pcaption' => 'required']);
         $path = request('post')->store('uploads', 'public');
         Auth()->user()->posts()->create(
           [
              'pcaption' => $data['pcaption'],
             'post' => $path,
            ]);
        return redirect()->route('home');
    }
    }