[Turtle91]

I'm not sure if there is a special ePub 3 function, or if you could get an effect like that with display:flex...but couldn't you get that with using float??

I haven't tested this...I'm taking a break at work ...but something like this might work:

div {float:left; width:100%; text-align:center; break-inside:avoid}

<div>
  <img alt="" src="test.jpg" />
  Caption text
</div>

<p>Other text.</p>
<p>Other text.</p>