That is about 95% true. Penalties that include loss of down are exceptions. No extension of the period for those fouls. Also, no extension of the period for fouls that result in a safety.
Fixing America's Poorly Functioning Public School Systems Might Require a Bulldozer
https://reason.com/2021/09/17/fixing-americas-poorly-functioning-public-school-systems-might-require-a-bulldozer/