Overvierwer 1.17 can ganarate maps from 1.12 

1. download sources and compile https://github.com/overviewer/Minecraft-Overviewer

OR

1. download precompiled (EXE file) Overviewer 1.17 from my server HERE 

2. download textures for 1.17 (compatible with 1.12) (full manual here)

3. create config file

worlds["survival"] = r"c:\world"

renders["survivalday"] = {
    "world": "survival",
    "title": "Survival Daytime",
    "rendermode": smooth_lighting,
    "dimension": "overworld",
}


outputdir = r"c:\output"
texturepath = r"c:\client.1.17.jar"