I figure most players won't be too bothered about the possibility of playing a hybrid character other than a Half-Elf or Half-Orc, but if you're the rare player who does (or if you just like seeing solutions to D&D problems) then I've got something that will help you out.

I have made a guide that will work out the race features to apply for any combination of the official races released to date (except the ones from the Ravnica book, which I don't have). Here's a link to the guide in Excel spreadsheet format:

Creating Hybrid Races in D&D 5e

Plus there are a couple of blog posts where I talk about playing hybrid characters and the process of making the guide (here's the first, here's the second).

I hope this is useful to someone, or at least amusing enough as an exercise. If not, it was fun to make anyway! Enjoy!