Yes it is possible to get electrocuted by a live wire even if you're not grounded out.
Lineman wear special gloves even when in the bucket so that they do not get electrocuted when working with live wires.
The lineman also use special insulated tools for connecting live wires and they must make sure that there gloves have no holes in them and if they have any holes they must be discarded.
So even if you're in a bucket up in the air you can still get electrocuted because that happened to a tree trimmer who accidentally touched a live wire while in his insulated bucket truck and he got killed.
So always be very careful around live wires even if you're not grounded out because you can still be electrocuted.
When lineman go crawl on power lines they get electricity passed through to their bodies so that they bond with the electricity which prevents them from being electrocuted so never go on a live power line even if you see a specially trained person doing so.