Migration of self-service procurement (Classic UI) customizations/personalization's to Redwood RSSP

Summary:

we are about to move our self-service procurement page (Classic UI) to Responsive self-service procurement (RSSP) in our instance.
But we have some customizations on self-service procurement page (Classic UI)(ex:making a dff mandatory based on other fields).
Now we need same customizations/personalization in RSSP page and we heard Sand box wont work here and we need to use Visual Builder. We need your support to move the customizations/personalization from Classic UI to RSSP

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