test.blade.php

<form action="test?test=query" method="post">
    @csrf
    <input type="hidden" name="test" value="post" />
    <input type="submit" value="blah" />
</form>

web.php

<?php

Route::view('test', 'test');

Route::post('test', function (Illuminate\Http\Request $request) {
    dd([
        'input' => $request->input('test'),
        'get' => $request->get('test'),
        'all' => $request->all(),
    ]);
});

/*
array:3 [▼
  "input" => "post"
  "get" => "query"
  "all" => array:2 [▼
    "_token" => ...
    "test" => "post"
  ]
]
*/