a buttinski here, but, as I read the decree, it only applies to various types of expiring residency documents and delayed applications related to them, and
NOT to 90-day tourist visas.
C. However, since the Migraciones offices have been closed since March 16, except for the border or airport exit/entrance where you cannot get the paperwork done, no paperwork for extensions (prorroga) or "rehabilitation with order to leave within 10 days" can be done. The Migraciones site only says that everything is shut down except for "emergencies". As far as I know, there has not been any change or modification or grace period for visas expiring during the lockdown. Perhaps, there may be in the future (or not), as there have been some amnesties in some other countries (not the US) for overstaying visas due to the virus. I assume that, at the present time, the normal fines for non-rehabiltated overstaying presently have to be paid at the airport for leaving late on a tourist visa, even if it is "not the tourist's fault" (can of worms) because of the virus lockdown situation (I do not know if this is accurate). This is all speculation and 3rd-hand info on my part, not hard fact, and I am notan Immigration lawyer here . Also, there may not be any special dispensation for tourist visas expiring during the border lockdowns. When "it" is "over", Migraciones may just shrug and say that the normal overstay procedure continues, tough luck. We will have to wait and see.
Sorry for the rambling writing, but it is not a simple issue.