Can a iMac 2014 which does not have a HDMI port work as a monitor for a mac book pro 16 inch 2012?

Please refer to Target Display Mode (TDM)

To be capable of being a monitor for another Mac via Target Display Mode (TDM), the 2014 iMac must be a Mid 2014 model. Late 2014 iMacs do not support TDM. The iMac must also be running macOS 10.13 High Sierra or older.

You have a typo in the Macbook Pro description; there was no 16-inch model in 2012. Might want to clarify.

The Mac sending the video signal must be 2019 or earlier with an Intel processor and a macOS version ot higher than macOS 10.15 Catalina.

Cables/adapters needed to make newer Mac work with TDM can cost as much as a nice free-standing externla monitor. Other disadvanteages of TDM:

• Uses too much energy
• Setup is tricky and some people never get it working.
• You may only have a mirrored, not extended, display

Apple started the deprecations of TDM in Late 2014 and threw the last shovel of dirt in its moldering face in early 2020. TDM is dead tech