<PackageReference Include="TimeZoneConverter" Version="6.1.0" />

<p id="test"></p>
@currentUtc => @currentLocal

<p>
<span class="date-local">
<div class="spinner-border" role="status">
<span class="visually-hidden">Loading...</span>
</div>
</span> (<span class="date-iso">@currentUtcIso</span> UTC)
</p>
<p>
<span class="date-local">
<div class="spinner-border" role="status">
<span class="visually-hidden">Loading...</span>
</div>
</span> (<span class="date-iso">@currentUtcIso</span> UTC)
</p>
<p>
<span class="date-local">
<div class="spinner-border" role="status">
<span class="visually-hidden">Loading...</span>
</div>
</span> (<span class="date-iso">@currentUtcIso</span> UTC)
</p>
<p>
<span class="date-local">
<div class="spinner-border" role="status">
<span class="visually-hidden">Loading...</span>
</div>
</span> (<span class="date-iso">@currentUtcIso</span> UTC)
</p>

<script>
var tz = Intl.DateTimeFormat().resolvedOptions().timeZone;
document.getElementById("test").innerHTML = tz;

var isos = document.getElementsByClassName("date-iso");
var locals = document.getElementsByClassName("date-local");

for (let i = 0; i < isos.length; i++) {
    var fff = luxon.DateTime.fromISO(isos[i].innerHTML, { zone: tz });
    locals[i].innerHTML = fff.toString();
}

</script>

@code {
public DateTime currentUtc { get; set; } = DateTime.UtcNow;
public string currentUtcIso { get; set; } = DateTime.UtcNow.ToString("o");
public DateTime currentLocal { get; set; }

protected override async Task OnInitializedAsync()
{
    var tzFrance = TimeZoneConverter.TZConvert.IanaToWindows("Europe/Paris");
    var tziFrance = TimeZoneInfo.FindSystemTimeZoneById(tzFrance);
    currentLocal = TimeZoneInfo.ConvertTime(DateTime.UtcNow, tziFrance);
}

}