Я получил ответ. Просто добавьте стиль как display: inlin-block; и удалите имя класса формы столбцов карт.
Новый файл index.cs html:
@foreach (var item in Model)
{
<div class="card border-warning" style="width: 18rem; display:inline-block;">
<div class="card-body">
<strong>@Html.DisplayNameFor(model => model.EquipmentName) : </strong>
<p> @Html.DisplayFor(modelItem => item.EquipmentName)</p>
<strong>@Html.DisplayNameFor(model => model.EquipmentSetValueTemp) : </strong>
<p> @Html.DisplayFor(modelItem => item.EquipmentSetValueTemp)</p>
<strong>@Html.DisplayNameFor(model => model.EquipmentProcessValueTemp) : </strong>
<p> @Html.DisplayFor(modelItem => item.EquipmentProcessValueTemp)</p>
<a asp-action="Details" asp-route-id="@item.EquipmentId" class="btn btn-primary">Details</a>
<a asp-action="Delete" asp-route-id="@item.EquipmentId" class="btn btn-primary">Delete</a>
</div>
</div>
}
![Result Image](https://i.stack.imgur.com/AoKzq.png)