If your in great shape and low body fat just eating a cup of jasmine rice makes the veins pop out..
Cardio and finding YOUR macros

As far as I know steroids won't help you to make more veins or make the ones you do have bigger. Low bodyfat and pumping up will bring them out.

With regard to what you are asking, genetics doesn't mean sh1t.

Steroids help significantly. But, training is what does it better than anything. See fig 2 and Fig 3 to understand how steroids might be sowing vein gains or how you can improve them whilst off-cycle...
See discussion paragraph 8 for an explanation of vein gains: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3612416

Just a thought: a strategy might be to attempt to make your biggest vein gains whilst off-cycle, then a steroid supported cut to make them visible (steroids to retain muscle, and therefore veins - with the veins being the waste-fuel supply route back to the heart and remaining needed due to muscle retention)

With regard to visibility, anecdotally speaking, my veins pop when lifting heavy. When I lift for max cell swelling, there isn't a vein to be seen. I would suggest taking note of whichever type of training seems to induce max vein swelling or appearance for you personally, and then implement it whilst playing with fat/water to make skin layers and underneath as thin as possible - obviously that type of training done off-cycle and on-cycle is where you will see the gains, with the diet and water manipulation making them visible.

Genetics play a large role as does of course consitantly being lean in regards to veins.

To answer your question, I have always found the EQ on a cut makes my vascularity pop. However many avoid EQ due to the high RBC it brings on. So as with everything , research is key

Then again, I am genetically predisposed to haveing veins and also remain at within a few pounds of my optimum look year round. Lowering bodyfat and staying consitantly hard is key.

Try lowering your sodium.