Despite the Nintendo eShop closure for new purchases, you can for titles you own through the "Updates" section in eShop settings or by scanning official QR codes. Homebrew Method (CIA Installation)
From a technical standpoint, this is (the update data) as opposed to the base game’s Title ID. On a standard, unmodded 3DS, this update is downloaded via the eShop. However, in the homebrew scene, users need the CIA (CTR Importable Archive) version of this update.
Like previous patches (v1.1 to v1.4), it addressed critical issues such as the Lumiose City save glitch