OP, I've heard that some orgs will have a group meeting to notify people, but I think most of that is for teams/groups that are outside of the US and Canada where the HR rules are different.
In the US, the manager is supposed to inform you. In some rare cases, the Sr Manager (if one exists) or the Director will inform you and it's usually a case where the manager is being impacted as well.
Usually, for announced LR's, the announcement is made during an earnings call and then within a few hours of the earnings call, your manager or higher will send you a meeting invite for first thing the next morning and inform you. They have 3 business days to notify you, but they usually manage it on the first day. Most managers will just call it a 1:1 or a meeting, and it won't have an agenda. I know one person who happened to be on PTO out of state for the week of the earnings call when a LR was announced and his/her manager had to read the HR script to him over Webex. I guess you could ignore text messages and phone calls from your manager if you're on PTO, but it's not going to change or delay your LR date.
The exception to the announcement followed by the meeting invite is when they do the "voluntary" LR like they did in '21 or maybe '22. They announced that an LR was coming, that "at risk" employees would be notified, and they could either voluntarily take the longer LR package immediately, or they could stay and try to find an internal role on another team in the next 30, 45, or 60 days--I don't recall how long it was--and if they didn't find a new role, they would be LR'd with a package that was shortened by the number of days they had to look for the new role. That effectively made the severance packages equivalent except that you spent your time working part time and looking for an internal job part time instead of just taking the money and running and looking for a job outside of Cisco instead of letting your peers that left early snag the good jobs currently out there while you tried to find non-existent internal roles that the ELT said you were going to be given higher consideration for over outside hires.
Which option the ELT goes with is unknown, but my bet would be on the former instead of the latter.