Topping or structure?
Another herb can replace basil as a topping with a different flavour. Eggs form the structure of a tortilla: removing them needs another formulation. Tahini adds sesame flavour and texture to hummus; omitting it creates a different purée.
Water, fat and leavening
Fresh tomatoes, passata and paste have different water contents. Drain or reduce for the intended use. Baking powder and bread yeast are not interchangeable in pancakes and pizza. White chocolate is not an automatic replacement for dark chocolate in mousse.
Check the new composition
A swap can introduce a new allergen. Wheat-free flour does not guarantee a gluten-free meal; sauces and cross-contact also matter. Read product labels. For a strict dietary requirement, choose a recipe designed for it rather than combining improvised swaps.