To edit ESM files you need compatible xEdit build. That means version 1.4.4r or later (October 2023). Do NOT use versions 1.4.4c or older.
After downloading extract the ZIP file, then rename the EXE file "xEdit64.exe" to "SF1xEdit64.exe". 64-bit version is recommended, and to work on Starfield files executable needs to start with "SF1".
Double click the "SF1xEdit64.exe" then let it work on first run to index the data, this will take 10 minutes or little bit more. It will let you know in the bottom status bar when it's done. Following starts will take 10-40 seconds.