I do not understand, is it not intended that when I use useCropDimensions: true, then it should use the crop I have now requested it? I get my pictures in 100X100 pixels large and no matter which crop I use then it is 100x100 pixels I have crops of 100x100 and 150x 150 and 250x250 pixels and I would like to choose the rest I want. why can't I

my code:

@foreach (var item in portfolio)
                {
                    //henter thumbnail billede fra portfolio
                    var thumbnail = (IPublishedContent)item.Value("thumbnailPortefolie");                   

                    <div class="col-sm-6 col-lg-3 artwork">
                        <div class="portfolio-box rounded my-3">
                            <div class="portfolio-img rounded">

                                <img class="img-fluid d-block" src="@thumbnail.GetCropUrl(useCropDimensions:true);" />

                                <div class="portfolio-overlay">
                                    <a class="popup-ajax stretched-link" href="@item.Value("linkTilHjemmesidenPortefolie")"></a>
                                    <div class="portfolio-overlay-details">
                                        <p class="text-white text-6"><i class="fas fa-plus"></i></p>
                                        <h5 class="text-white font-weight-400">@item.Name</h5>
                                    </div>
                                </div>
                            </div>
                        </div>
                    </div>
                }