I’m a long time user of Ctrl+x 8 Return for inserting arbitrary Unicode characters. I use it, for instance to insert the red meat character (🥩) for my Red Meat Friday posts.
For mundane accents like é, I use ivy-insert-org-entity that I stole from John Kitchin’s Scimax. It’s lighter weight and easier to use for spelling peoples’ names or using the occasional foreign accented word.
Even though I’ve been using Ctrl+x 8 Return for many years, I had no idea of how powerful the command is until I read this post from Rahul M. Juliato. It turns out that in addition to just using an existing Unicode character you can compose accented characters manually, combine multiple code points into a single glyph, and much more.
Juliato’s post is long and complicated so I won’t try summarize it here. You really need to take a look at the post itself. I had difficulty making some of his examples work but that was probably me doing something wrong or a shortcoming of my fonts. If you’re like me, you’ll probably never need all the power he describes but it’s nice to know it’s there if you do need it.