Hi there, who is waiting for the text highlighting feature!
Although this feature has not yet been implemented, 2 years ago I found and published a hack in the Figma Community that allows you to achieve this. You can duplicate and explore the file from this link: Hacked Auto Layout with Multiline Text Highlighted file by Yury Zeliankouski | Figma Community.
There is also another way that I shared in this thread: How to have background colour for text only and not the entire container using auto layout - #4 by tank666.
Yes, this is not a solution, but very complex workarounds that are not stable enough and are error prone.