Automation rules can help you adjust CPT bids based on your target metric (CPI, CPA, ROAS, etc.). For example, you can select CPI as a target metric. In this case, your CPT bid will automatically be adjusted based on the current and target Cost per Install. Or, as another example, you can choose to automatically optimize bids based on the target Cost Per Goal you would like to achieve.
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Below are several points you need to remember before applying this action.

Ensure there is enough historical data for the keyword to which you want to apply this action. Otherwise, it may reduce your impressions volume. To set aside keywords without data, we suggest you specify the following conditions:

It is especially important to avoid using this action on keywords that have no Taps/Spend. Here is why: the system uses the Taps metric to calculate a new keyword bid. For example, to adjust bids based on your target CPI, the system will use the following formula: Bid = (Installs / Taps) * Target value. If Taps = 0, to avoid setting bids to 0, it will set them to the lowest bid limit you specified. As a result, for keywords like that, you may be missing opportunities to reach your target audience.
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In this article, you can find the formulas used by Adjust bid by target metric action: Adjust Bid by Target Metric: How the Bids are Calculated?
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It is important to understand that your desired target value is realistic. You can get this number from benchmarking and the historical data of your keywords. When time passes, you will be able to notice some patterns that will help you calculate realistic target values.

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Applying this action separately to different campaign types (Brand, Competitor, Generic) is important. Some campaign types are more expensive than others. They usually don't share the same desired values of target metrics, so you may want to adjust the CPT bids independently. For that, we suggest that you create separate automation rules for different campaign types. This approach works especially well for the account structures that contain brand and tier campaigns.

Remember that, like with campaign types, some storefronts can be more expensive than others. So your KPI values for different countries/regions may differ. That's why we recommend creating separate rules for various storefronts and setting realistic values for the target metric.

The Adjust bid action works best on Exact Match keywords. Although you can apply it to Broad Match keywords, it is not recommended. You need to know the metric's target value, which is possible only with Exact keywords.

You will see the best results if you apply this action to the keywords that already perform well — adjusting bids here will potentially scale good performance.

What about underperforming keywords, that is., those that convert but seem too expensive? First, decide what is an underperforming keyword in your case and how much you are willing to spend on a keyword to check. If you want to optimize them, set their CPT bid limits wisely. A lower bid limit will ensure that these keywords will still get into the auction, while an Upper bid limit will prevent overspend. Don't use this action on spend wasters, that is, keywords that eat your budget up but hardly ever or never convert. To set aside keywords like that, add the relevant metrics to the conditions: Spend, Goals, Installs, Downloads, CPI, Impressions, Taps, etc. However, while adding these restricting conditions, don't forget to set a good date range, for example, use data from the last 14 or 30 days).

When a keyword doesn't perform for a long time, it makes sense to pause it or add it to negative keywords to prevent wasting spend rather than adjust its CPT bid.

In the Conditions section, set a tolerance window — a range for your target metric that you will see as an achieved result. What does it mean?

For example, you want to adjust the keyword CPT bid by Cost per Install = $5. However, $4.50 and $5.50 will also be realistic and good values for you, so you do not want to adjust bids further as soon as your CPI achieves them. To prevent unnecessary bid changes, you can set the following conditions: CPI is not in range of $4.50 and $5.50. 

In such a case, if your target value is $5 and your current value is at $5, the rule won't scale your bid.

Don't set your Lower bid limit too low. A lower bid limit ensures that the keyword continues to get into the auction. If you fall below this bid, you may cut the traffic, affecting the other metrics down the funnel.

Don't run this action too frequently. It requires some time for changes in a bid to affect your target metric.
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It is also important to carefully choose the lookback period for the rule (The date Range the rule will check based on the selected conditions).

Run the rule for some test period, say 1-2 weeks, and monitor its performance. If you notice negative results, consider specifying additional conditions to limit the action coverage or reconsider the value you currently use as a target.