You would have to convert the ebook to mobi with the PDOC option selected. Unfortunately, mobi is an old format and has limited font options, extremely limited CSS and limitation on images which must be sized in absolute measures (no setting an image to 25% of width for instance).
Send to Kindle is an Amazon service. You can send to Kindle from calibre but that needs setting up a email relay using a service such as GMX, a Sent to Kindle app (I've palyed with StK for Windows) or using the Send to Kindle website (the one I use for testing is
https://www.amazon.ca/sendtokindle. Note that I am using Amazon's Canadian website so the .ca TLD.
There are almost religious arguments about whether using StK where Amazon retains a copy of the ebook in their cloud is an acceptable security risk.