Use a normal link to submit a form

This post shows you How to submit a POST form using the <a href="..."> tag.

By default, In ASP.NET Core you can see your logout form as shown below.

<form class="form-inline" asp-area="Identity" asp-page="/Account/Logout" asp-route-returnUrl="@Url.Action("Index", "Home", new { area = "" })">
    <button type="submit" class="nav-link btn btn-link text-dark">Logout</button>
</form>

If you want to use hyperlink to submit a form you can modify your html code as shown below.

<form asp-area="Identity" asp-page="/Account/Logout" asp-route-returnUrl="@Url.Action("Login", "Account", new { area = "Identity" })">
    <a onclick="this.parentNode.submit();" class="dropdown-item btn btn-outline-grey btn-h-lighter-secondary btn-a-lighter-secondary">
        <i class="fa fa-power-off text-warning-d1 text-105 mr-1"></i>
        Logout
    </a>
</form>

As you can see, I'm using a link tag to submit a form with JavaScript by clicking a link.