The phrase "is appropriate" is a common term used to express suitability or correctness. However, there are many other synonymous phrases that can be used in its place to add variety and nuance to your language. For example, phrases like "is fitting", "is proper", "is suitable", "is befitting", "is applicable", and "is relevant" can be used interchangeably in many contexts. Additionally, you might use more colloquial expressions like "is spot on", "is just right", or "is exactly what's needed". By varying your language and using a range of synonyms for "is appropriate", you can add interest and clarity to your writing or speech.