Unless you’re marinating in something enzymatic, like pineapple or papaya, you will not tenderize your meat. Acids won’t do ti either, unless you’re dipping your steak in the stuff they use to bleach cement floors. What an acid like lemon juice or vinegar will do is stimulate your mouth to release more saliva, which in turn tenderizes the meat as you chew. But…not that much.
Your best bets are cut, time, heat, and proper service.
There’s a good answer or two here dealing with sous vide. I looooove sous vide. It is, for me, one of the best ways to make a decent steak. But it’s a bit pricy and not for everyone.
First off, know your cuts. A top round steak will NEVER be tenderloin tender, no matter what you do. It’s not structured like that. But top round steaks can be sliced veeerry thin and used as perfectly great hot-and-fast sandwich steaks. A flank steak has a lot of “grain” to it, as does a skirt or a hangar. It benefits from some care in preparation. A brisket is tough and full of fat and connenctive tissue - that won’t ever make a good steak but is perfect for BBQing or slow-cooking.
Second, know what time and temperature you need. You CAN turn a short rib into something fork tender by cooking very slowly over a low heat (i’ve done the sous vide 72-hour short ribs and they’re amazing) but even a few hours in a crock pot with a little braising liquid can work wonders. Meanwhile something like a ribeye will get tough if overcooked, as all the tender fat melts out. Get your temperature right for a hot sear and cook it fast. (or: use the modernist cooking way - sear a frozen steak on a scorchingly hot pan and then put it in a 200 degree oven for exactly an hour. There are a lot of methods, and almost all are about precise temperature control.)
Finally, know how to cut and serve. Remember the grain of a flank or a skirt? Try to cut that with the grain, no matter how tender you get your steak it’ll be stringy. Cut against the grain, and suddenly you have short little bundles of meat grain, full of flavor. A thinly-cut flank is one of my favorite foods, period.
To be perfectly honest, butter-tenderness is not the be-all of steaks. It’s rare, short of a mind-bogglingly expensive wagyu cut, to find something like a sirloin that is capable of getting all the way to that cut-it-with-a-fork stage. You can get tehre pretty easy with a tenderloin but tenderloin is pricy and quite frankly fairly bland as steaks go. It’s not a muscle a cow uses much so it stays tender but also never builds up a lot of those elements that produce good flavor. It has hardly any fat on it, and fat is where a lot fo the flavor sits.
Marinating isn’t a bad thing - in fact certain cuts benefit highly from it in terms of flavor. But it won’t get your steaks tender. I recommend picking up a good book on grilling - even if you don’t have a grill - from your local library or bookstore and you’ll find a wealth of info about how to cook various cuts of beef, nearly all of which can adapt well to a standard home kitchen.