If you don't know what is dynamic arrays, then just read this article https://exceljet.net/articles/dynamic-array-formulas-in-excel.
Note, dynamic array's functions like UNIQUE, FILTER, SORT, etc. were already implemented early. But other new general dynamic array features were added to LibreOffice Calc only now into current master that will be 27.2 release in next year.
Let's say big thanks to Collabora's developers for it, because all work was made for Collabora Office and then Xisco Fauli copied all patches to LibreOffice project (The source code license allows it, because it's the same MPL 2.0 on both sides).
You can try the new features using master daily builds for your OS by the link.
