It sounds like you are asking if it’s OK to add additional baking soda, beyond what is called for in a cake recipe, is that right? The problem with this is that chemical leaveners “tenderize” a cake, weakening its structure. If you weaken the cake’s structure too much, it can dip in the middle or even collapse. Also, altering the pH of the batter to be more alkaline will delay setting of the eggs, which can coarsen the texture of the crumb. You might be able to get away with adding a tiny amount, but then again you might not- depends on how much structure is in the recipe to begin with.
If you want more air in the cake, try beating the butter and sugar longer, and maybe separating an egg or two and beating the white separately, gently folding that into the batter at the end. Or you might just look for a different recipe, one that is designed to be light and fluffy: perhaps a sponge-style cake?