jq ' from_entries'

cat data/ann.json | jq '.metadata.annotations | to_entries | map_values(.value="override-value") ' cat data/ann.json | jq '.metadata.annotations | to_entries | map_values(.value="override-value") | from_entries' 
[
  {
    "key": "deployment.kubernetes.io/revision",
    "value": "override-value"
  },
  {
    "key": "machine.openshift.io/owned",
    "value": "override-value"
  },
  {
    "key": "label1",
    "value": "override-value"
  },
  {
    "key": "label2",
    "value": "override-value"
  },
  {
    "key": "label3",
    "value": "override-value"
  }
]
    
{
  "deployment.kubernetes.io/revision": "override-value",
  "machine.openshift.io/owned": "override-value",
  "label1": "override-value",
  "label2": "override-value",
  "label3": "override-value"
}