I caution the use of emoji, I've seen so many stack overflow job posts with memey use of emojis and it just makes me cringe and I find it hard to take the company seriously.
(I was shocked the first time I got spam that started playing animations before I opened it.)
https://www.outreach.io/blog/will-emojis-increase-reply-rate...
Maybe SO emails go over the top though
The linked report actually indicates a decrease in replies.
Combined across all seven test variations, we saw a 42% decline in reply rate when the subject line featured emojis.