How Import an existing schema (POST) instead build on on your own

Hey to all of the AppGyvers out there, I hope you are all well,

I have another question today.
How can I import a given schema instead of having to build it myself?

In the following situation, I would like to dynamically generate a QR code via an API when opening a page, e.g." RapidAPI "or something like that. in this case, I have fixed specifications such as the scheme for the Request should look like.

Now the Question: How to Import the schema first … and then replace all the static demo values ​​with my dynamic page.vars from Composer Pro?

That was it for today, everyone has a good night’s sleep and I’m looking forward to your feedback tomorrow. Thanks very much

Jens