If I do an image search for TO-254 I see packages that look like they were made in the '70-ies.
Clicking through on a link however suggests that they’re used for SiC (which has very high operating temperatures of several hunderds degree Celsius, so packaging becomes the limiting factor)
Making new footprints in KiCad id a breeze however. I would not even consider searching the 'net for more then 2 minutes to find a footprint for a simple 3 pin THT part like this.
KiCad’s Footprint Editor works well, is nicely integrated with the rest of KiCad and it’s UI is very much the same as for Pcbnew. The most complicated part of it is the library management, because KiCad’s own libraries are read only, you have to put custom Footprints in a custom library.
This is a good start:
This is also good:
Although you probably do not even have to start from scratch.
You can easily start from a copy of a regular TO-220 or TO-247 and adjust things a bit to your liking.
There are also sites such as snapEDA where you can find Footprints, but these sites seem to be more trouble than they’re worth. A common problem with these is graphics on Edge-Cuts layer which is not handled well in KiCad, and (figuring out how to) repair it is more work than designing the thing from scratch in the first place.