How to set headless VNC resolution using real VNC

How to set headless VNC resolution using real VNC?

I am using Raspian Stretch and I can not set the resolution of my desktop when using VNC headless. I am using Real VNC because it comes by default (I have it configured there). I have no monitors

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1. Comment these line in /boot/config.txt  

sudo nano /boot/config.txt

    [pi4]
    # Enable DRM VC4 V3D driver on top of the dispmanx display stack
    # dtoverlay=vc4-fkms-v3d
    # max_framebuffers=2

    [all]
    # dtoverlay=vc4-fkms-v3d
    [all]
    # dtoverlay=vc4-kms-v3d

2. Open raspi-config and change to new resolution in 2 Display Options > D1 Resolution

sudo raspi-config