Well, of course you can tuck a "dress shirt" into jeans -- but the jeans should be top quality, be unadorned (or Levi's) and fit you well. (cf. APC New Standard or Petit Standard) And the shirt should ideally be slim but not darted (Gitman Vintage, Band of Outsiders, BB Slim or Extra Slim Fit), and it can't be pressed (light ironing is fine.). Preferably a button down collar
I often wear a Gitman Vintage or BB slim fit oxford with raw denim.
Another way to wear it -- find a beat-up old BB oxford, wear with faded 501s and a bridle leather belt with aged brass buckle. Insert feet into dirty bucks = be a chick magnet.
The key here is that you need to be in shape. That automatically excludes about 80 percent of male population.
My personal rule is that if I'm wearing a button down shirt with jeans, if I'm wearing a jacket, I tuck it in. If the shirt is the top layer, whether over a T-shirt or over nothing, it's usually untucked.