Users searching for jpg to ttf conversion are typically looking for a way to create TrueType Fonts (.ttf) based on a picture, probably of some kind of text. This is not impossible, but certainly not something you do with a single click.
You will have to use some tools that can be used to create fonts and that also supports import or reuse of raster/bitmap graphics. Vector graphics would be the preferred source of material for most font tools though.
Updated: August 14, 2023