Will Ukraine Referendum Lead to Full-scale War?

On September 30 President Putin is to deliver a message to the Federal Assembly of the Russian Federation to announce the results of the referendum held in four "former" regions of Ukraine.
A section of the Russian media conjectures that Putin will likely issue an "ultimatum" to Ukraine to withdraw its forces from "Russian territory," which Kyiv is almost certain to rebuff.
With Ukraine and its Western allies asserting not to recognize the results of the refrendum, and announcements from the Kremlin that attacks on the four regions will be treated as "an attack against Russian territory," a full scale war seems imminent.
As Kyiv, propped up by its Western allies may launch a full-scale assault to re-take territory lost to Moscow via the refrendum, the Kremlin may respond with greater force which is most likely to put an expanded number of civilian and commercial targets in harm's way.
Voting began on Friday in Donetsk (DPR) and the Luhansk People's Republics (LPR), which Putin recognised as independent just before the invasion, and Russian-controlled areas of the Kherson and Zaporizhzhia. The voting is expected to go on till September 27.
After counting the results, the bills on the inclusion of new subjects in the Russian Federation will be submitted to the State Duma on September 28. On September 29, the document can be adopted in the Federation Council.

Is Russia preparing for an all-out war?
The "partial mobilization," of Russain reservists is an event tied to an anticipated increase in hostilities and not just to fill the positions of the some 5700 servicemen (officially disclosed Kremlin figures) killed in Ukraine.
That the mobilization was preceded by an amendment to the Criminal Code in which penalties have been prescribed for non-fulfilment of the state defense order is another indication of wartime push for arms manufacture.
Once the Kremlin puts its seal on the result of the refrendum, the possibility of returning the former Ukrainian regions back is ruled out diplomatically; which leaves Ukraine and its Western allies with only the military option. It remains to be seen who issues the declaration of war first- Kyiv or Moscow.
In the event of a declaration of war, Russia will demand a stop to any supply of weapons to the Armed Forces of Ukraine. Or else any country that supports Ukraine militarily could risk being at war with Russia.