There are some cool things you can do in email, but if you’re a team of one trying to get stuff done, the rule to live by is this — is it going to make my life easier, or is it going to be a distraction. The chances are doing more email at a “simpler” level will have more benefit than one thing that’s very complicated.
Nevertheless, these are some fun things:
Live Imagery - you can make images change in real time, at the point where the recipient opens their email. That means if you have a 48 hour sale and they open 47 hours in, you can say “Quick, only 1 hour left!” and have a countdown. Be careful about any accessibility issues these things create, though.
Interactive email - you can make carousels and click-to-reveal content, which, when used with interesting content, can make email more engaging. Support for this across email clients is, however, patchy — you'll need to build fallbacks and control when and where they show.
AMP4Gmail - this may or may not bring more sustainable ways to create interactive email. On the main, it's available in Gmail if you jump through some hoops (which makes sense as AMP was initially a Google project). It is somewhat controversial as it is seen by some as a land grab of the open nature of email. Regardless, you'll need a sending platform that supports it — and once you have that, you'll need to incorporate an extra code build into your email process.
Video in email - it’s possible in some email clients (mainly Apple laptops and iPhone/iPad), but complicated. An easy win is instead to have a screenshot with a play button (you could make an animated GIF if you fancy it), and then get people onto a landing page.