I visited this WHS in Summer 2019 and I stayed in Olomouc for 1 night. Olomouc itself is very pleasant place in Moravia to explore in Czechia and it has a lively square with splendid fountains and statues which I found far more interesting than the ones which were recently inscribed in Augsburg, Germany.
The only monument that really stands out though is in fact the inscribed Holy Trinity Column, one of the smallest inscribed areas on the WH list. On the floor just in front of the column chapel entrance is the UNESCO WHS inscription plaque. The nomination dossier is an essential read to better appreciate the column's importance but I felt it didn't possess enough OUV. It's a very interesting peculiarity of most Central European towns and cities but that doesn't mean it deserves inscription on its own.
The best light for photography is in the morning when the statues and over-the-top decorations of the column shine bright (even though the stonework needs cleaning from pollution - quite a problem in Czechia as car-free areas are almost non-existant). I really liked the Art Nouveau facade details of two buildings just behind the column which reminded me of Riga, Latvia.