使用target属性，所发生的只是DOM容器.swal2-container被追加到目标元素，但它具有position: fixed;样式，您需要如下所示覆盖它：

$(document).ready(function() {
  var id = document.getElementById('trial');
  Swal.fire({
    title: 'I will be placed inside the #swal2-container',
    toast: true,
    target: id,
    position: 'bottom-left'
  });
});

#trial {
  position: relative;
  left: 50px;
  display: block;
  height: 200px;
  width: 500px;
  border: 1px solid;
}
.swal2-container{
  position: absolute !important;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/sweetalert2@9"></script>
<div id="trial"></div>

SweetAlert2有一个customClass属性，你可以用它来添加自定义类，这包括到container。所以你可以只创建一个专用的类，并为你的特定吐司添加它（或者如果你使用Bootstrap 5，你甚至可以使用position-absolute）。

$(document).ready(function() {
  var id = document.getElementById('trial');
  Swal.fire({
    title: 'I will be placed inside the #swal2-container',
    toast: true,
    target: id,
    position: 'bottom-left',
    customClass: {
      'container': 'trial-swal-container'
    }
  });
});

#trial {
  position: absolute;
  display: block;
  height: 200px;
  width: 500px;
  border: 1px solid;
}
.trial-swal-container {
  position: absolute !important;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/sweetalert2@11"></script>
<div id="trial"></div>