The USGS provides detailed downloads of fire perimeters, with timestamped files that can be used to show the spread of a major fire over time.
Using the 2017 Thomas fire as an example, we'll process this data into a single SVG file with all the different perimeter measurements.
This index page contains links to a series of shapefiles of the fire boundary, each one with a timestamp:
https://rmgsc.cr.usgs.gov/outgoing/GeoMAC/2017_fire_data/California/Thomas/