I am a specific legatee of a man who died in 2018. In 2019, I requested delivery of the legacy from his widow, who did not respond. Can I still claim my legacy?

In principle, no. Case law generally limits actions for delivery of a legacy to a five-year period from the date of death (Art. 2224 Civil Code; Cass. 1st Civ., 21 June 2023, No. 21-20.396 FS-B).