Recently i have successfully printing a test page from my HP printer on my OpenBSD 6.7 laptop after reading and practicing an article on website of mp-5 text editor (see it on my other post). I use following step.
1. add required packages using pkg_add cups gtk+3-cups hpcups hplip.
2. edit /etc/rc.conf.local as follow on pkg_scripts section.
3. restart openbsd.
4. open browser and go to localhost:631 to open cups admin page.
5. On administration tab click add printer and input root and password if required.
6. Choose other network printer -> .
7. On connection textbox type ipp://[printer ip address]/ipp/print.
8. On next screen fill name and description.
9. On next screen select HP on make combobox.
10. On next screen search printer model as follow.
11. Click add printer button and we are done !