From the FSSP Liturgical Ordo:
“April 27, 2025, Divine Mercy Sunday: A plenary indulgence is granted to those who take part in the prayers and devotions held in honor of Divine Mercy, or who, in the presence of the Blessed Sacrament exposed or in the tabernacle, recite one Our Father and the Creed, adding a devout prayer to the merciful Lord Jesus. Those who for a just cause cannot get to church can gain the same indulgence by reciting one Our Father, the Creed, and a devout prayer to the merciful Lord Jesus before an image of the Divine Mercy.”
Note: The usual conditions for plenary indulgence (see link above) also apply. See if your parish is celebrating Divine Mercy Sunday with special devotions and use that opportunity to obtain the indulgence. Let your pastor know you appreciate this.