Q: Is it possible to bless the Oil of Catechumens and the Oil of the Sick and consecrate the Holy Chrism at a Mass other than at a diocesan Chrism Mass with all the priests attending?
A: Whenever a bishop blesses and consecrates the oils, he does it at a ceremony called the Chrism Mass, using the appropriate prayers and rubrics from the Roman Missal and the Roman Pontifical. In 2020, amid the pandemic, Pope Francis allowed bishops to postpone the chrism mass.
All the priests do not need to attend. In my diocese, the bishop celebrated the chrism mass with about 5 people present this year.