In japanese, we say サイズアップ（size up）meaning “ to change the size from small one

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We wouldn't say it like that, it would sound a little weird in English in that context. What you would say is: "We would like the tube to gradually get bigger for the treatment." We would just say we want something to be bigger or smaller. In English, size up is used like a idiom in the context of observing something, someone or a situation before forming a opinion or making judgement. Example: "The boxer stares at his opponent, sizing them up to understand the level of their strength. He will decide how to act afterwards."
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