The MultiColumnComboBox does not use a Grid component internally. This makes it more light-weight and performant. As a result, Grid features cannot be easily enabled, unless we implement them once again in a different context. A better option is to allow developers to render a Grid via some template or by exposing the popup container. Then, enable any Grid features that you need.
For the time being, I am leaving this feature request with a "Need More Info" status. Everyone who needs Grid-like features (for example, column resizing, sorting, etc.), please list here which specific features are important for you. We might implement some of them in the MultiColumnComboBox and leave all the others for the "template" scenario with a full-blown standalone Grid.
Virtual Classroom, the free self-paced technical training that gets you up to speed with Telerik and Kendo UI products quickly just got a fresh new look + new and improved content including a brand new Blazor course! Check it out at https://learn.telerik.com/.