Will the following complex show optical isomerism
As already commented by Ivan Neretin, the cis form also does not show optical isomerism. Elaborating a bit further on the comments: 

Complexes show optical isomerism when they are asymmetric (also known as chiral). They should not have any elements of symmetry, such as planes/axes/centres of symmetry. The trans form has a clearly visible plane of symmetry. It's a bit trickier to find the plane for the cis form. Here's a diagram showing the planes:

(source: Chemistry libretexts)