If you've picked a somewhat extravagant, unusual first name, it can be nice to create some balance by opting for a simpler, more classic baby girl middle name. Anna is the perfect option. Because it begins and ends with an "a" vowel, this name flows perfectly with just about any first and last name.
According to BabyNames.com, Anna is a Hebrew name that translates to mean "gracious" or "merciful." It's an extremely common name — in the U.S., it was the 68th most popular girl's name in 2020, according to Behind the Name. This means that it may not be a great choice for a first name, as plenty of other babies will share your child's name — however, as a middle name, it's a solid choice.
One thing to bear in mind if you're planning on using Anna as a middle name is that your daughter's middle initial will be an "A." So, if her first and last name initials are consonants, you may end up accidentally spelling a word with her initials. For instance, if her first name was Cara and her last name was Thompson, her initials would spell "cat." Whether you think this is a good thing or a bad thing, it's definitely something to keep in mind!