Test 220V 50 Hz signal using oscilloscope
Yes - sort of.

You will rely upon the ground connection that your scope has in its power cord.  That means that you do NOT ever connect the ground wire from your scope probe to the power circuit that you are measuring.

The only safe way for you to do direct measurements on an AC power line is by either having an isolation amplifier between your probe and the scope OR to use a scope that has isolated inputs.

I have an older Tektronix THS720P - this has two scope input channels and one set of DMM lead connections.  All 3 of these input channels is isolated from each other as well as any external connections to the scope.  This scope is rated for working with 600 Vac power systems and motor drives when used with the appropriate probes.

Tek does make a modern equivalent to this - it's fairly expensive but there are also less expensive options available.

For example, you can purchase an analog isolator intended for scope use.  I think that the isolation barrier on the one I was looking at was rated at 2500V peak AC + DC.  I'll see if I can find a link to the one I was earlier.

The low-bandwidth versions are fairly inexpensive.