I don’t know if these are well known, if they aren’t, give them a try.

Tomato sauces, if they are a bit bland try adding a dash of soy sauce.

If you want a ‘Beefier’ taste in a dish, add Vegemite/Marmite, it’s all umami and really helps. You can make Vegetarian French Onion Soup using it and meat eaters will love it.

Mushroom soup/ sauces, add cinnamon (preferably cassia, not true cinnamon). Just a small amount, below the threshold of where you can identify it as an ingredient. Iirc something about the phenols in the cassia boosts the mushroom flavors.

ETA: based on another comment, chocolate sauces/ Ganache, add vanilla and espresso. If you want the most delicious Reese’s peanut butter cup cheesecake, ice cream etc. You want a shot of espresso and a touch of vanilla.

If you have not tested yourself to see if you are a Supertaster, you should. It makes a world of difference when you are cooking for other people.

If you have others please add them, these are some of my favorites.