Indirectly, yes. Export your Switch Mii as a QR code (using the Switch’s Mii Maker), then import that QR code into Citra’s Mii Maker.
For many 3DS games like Tomodachi Life , Mario Kart 7 , or Super Mario Maker , having a Mii is not just a cosmetic choice—it's a requirement to play. However, because Citra is an emulator and not a full console, it doesn't always come with the system applications like pre-installed. citra mii maker download