Is it mentioned in the Sunnah of the Prophet, peace and blessings be upon him, that condolences should be offered at the grave, and what should be written for someone who requested that their condolences be offered at the grave instead of setting up mourning tents?

Rejecting the setting up of mourning tents and accepting condolences through modern means is commendable, as is rejecting all innovations introduced by people in funerals. There is no specific text regarding offering condolences at the grave, but there is no harm in the deceased's relatives standing in a single line at the cemetery to receive condolences. As for what is written in the will concerning this matter, it is a recommendation to adhere to the Sunnah (definition) and avoid wailing, mourning gatherings, and funeral innovations.