these are columns, your object seems flat. Apart from that, your object looks like modern, clean and brand new plastic or metal, while what you show is old stone monument, so it needs much more bump, spots, accidents, etc...
– moonbootsJan 12 '21 at 17:18
Okay thank you for your avices. Would you agree to receive my file to apply your advices and show me ?
– FrancNovationJan 12 '21 at 18:31
maybe check this for the texture: https://blender.stackexchange.com/questions/5699/creating-a-procedural-stone-texture ... also, you need to create some real bumps on your topology (you can use the Sculpt mode for that)
– moonbootsJan 12 '21 at 18:35