You can select multiple bidding strategies depending on your objectives, so you can optimize your campaigns:
Manual CPC: If you want to set up a maximum cost-per-click, choose this option.
Target CPA: You can select a target CPA for your ads within the “Campaign” tab. And if you have a CPA column in your feed, you can use this one in the next tab “AdGroup”, whereby you would have to select “Use a goal from my feed for Ad Groups”.
Maximize Clicks: Choose this option if you want to use the Google Ads Bidding Optimizers, reaching the highest number of clicks within your selected budget.
Maximize Conversions: Choose this option if you want to drive the highest possible conversions using a Google Ads Bidding Optimizer, choose this option, so based on account historical performance