I'm not sure if there is a platform for that.
Call to action (CTA) are usually something visual, in your website, that stand out from the rest of the page, with that you lead the user to interact with it.
There are tools that will tell you where the user looks and interacts more often, for example, hotjar creates a heatmap of user interaction, and with that you can position the CTA in those places, to lead the user into a successful convertion.
CTA is presentable on any platform. In fact, that is how marketing works.
You should not use too many CTAs in your sales pitch on any platform as that may distract the user from the actual product.
Every marketing platform has an option for including CTAs on its pages.
Don't overuse them.
Including more CTAs does not mean you will have more conversion.
CTA conversion is now a days very powerful systems. You can just try it with max bounty and any affiliate networks where people just enter their data and the money is moved to your account,but the only defect is that your affiliate manager he/she should accept you,then you may see for free traffic and spread your word and get conversions.
If you are asking about online services which provide Call to Action facility on your site. One free is Sniply and Hello bar. Sorry I am new member so they won't allow me to post its links, you can search on google. others which I know is a mostly indirect one like newsletters, Subscription form, etc. Try giving some freebies to your audience, this is what in trends.