M2 Product Variation Issue

I am new to Magento 2

My business have different variation for different product.

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However, in M2, I noticed that you will have to create an attribute manually for each product.

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For example: Product A with Product A Variation.

But when I try to create product b, there is a choice for product a variation.

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For now, I do have very less product so this is not an issue to me, but what if I have 100+ products and variation next time? Can anyone help me on this? Thanks!

A sample screenshot of what is the issue: Link