The official dimensions of the PS5 has yet to be revealed, but based on the images of the console released so far, the PS5 is expected to be a fair bit larger than the PS4 Pro.
According to multiple comparisons, the PS5 is expected to be several inches taller than the PS4 when stood vertically. Event width wise, the console will be wider than the PS4 and PS4 Pro.
According to Reddit user GREB07, the PS5 will tower over all existing consoles, including the Xbox Series X. In terms of width, it will be similar in size to the PS3 (original model) and the Xbox One: