Hi there, welcome
appropriate search terms to find articles in the area. Some authors will publish their scales as part of their articles (remember to cite appropriately if you use a scale or question from an article), whereas others may be willing to provide them via email with certain conditions.
Be cautious about the idea of "already validated" scales, by the way - validation is always an ongoing process, where the standards are always somewhat subjective and often changing. You will need to critically discuss the validity evidence that exists for whichever scales you do end up using.
Let us know if we can help further,