You should be able to. The first step is to run the POST command in something like Postman (outside of Thunkable) and make sure you can get it to work. If that works, then you can look at examples of POST calls on the forums and set up your blocks in Thunkable.
It’s going to look something like this: How to use web api with post + parameters and with form - #11 by muneer or this: Post header - SET HEADERS method - #9 by umester2020mxtl.
But again, the first step is to make sure it works outside of Thunkable.