unable to bake runny batter recipes
I bake a lot with gluten free (I cater for a wheat allergy) and as a direct result a lot of my batters are runny but I still get a fluffy final cake. Bread doughs are more like batter than bread too.

You mention folding in the comments, which prompts me to wonder if you're making a red velvet cake, given the recipe points mentioned.

If that is the case, you need to aerate the egg whites separately, and fold them in last, taking care as to not lose the air you put in.

If you edit your post to include the recipe that would help with diagnosis a lot more.