You have a Google Ad Campaign using an automated "smart" bid strategy like Target CPA, Max Conversions, Target ROAS or maybe even Max Clicks and you're dying to know if you're able to make bid adjustments (i.e. percentage increase/decrease). Google certainly doesn't restrict you from making these adjustments on various dimensions (e.g. location, ad schedule, device, audience, etc) or tell you they won't work but are they actually working?

If you dig into Google Ads documentation on the topic, you'll see that for most automated bid strategies the only bid adjustment that works is -100% on the Device level. The only exception is Max Clicks bid strategy. With Max Clicks Google Ads does indeed recognize any bid adjustment you make across all dimensions.

You can see this helpful table here in their documentation that will set the record straight:

Even though you can't make bid adjustments with most automated bid strategies, you can still exclude dimensions that are just showing to drive up cost with little to no conversions. So for example, let's say you notice age group 18-24 or lower 50% household income is just driving up cost without converting, you can exclude them to help reduce wasted ad spend, increase conversion rate and lower cost per conversion.