The candidates have to physically participate in the written tests. The telepresence is not allowed.
The candidates coming from abroad, can come to Italy without having to put themselves in mandatory self-isolation. In this regard, read the official website of our Ministry of Foreign Affairs, and in particular the part in which it has been written that for persons travelling to Italy for a short stay (72 hours, extendable for justified reasons up to 120 hours in total) for proven work, urgent or health reasons, the mandatory self-isolation is not required. The participation in a public competition is certainly one of the reasons for work.
As for oral tests and commissions, participation can be remote.