copy any web-based image url and paste using markdown link format. hereās a sample https://forum.obsidian.md/uploads/default/original/3X/2/6/26fd792a2dd1412e4c0e4cd6868911aa4ba3654e.png
replace the alt text with a number to resize the picture e.g. 
observe the image size in Live Preview (obey the sizing) vs Reading View (ignore the sizing)
SYSTEM INFO:
Obsidian version: v1.3.5
Installer version: v1.3.5
Operating system: Windows 10 Enterprise 10.0.19045
Login status: logged in
Catalyst license: insider
Insider build toggle: on
Live preview: on
Legacy editor: off
Base theme: dark
Community theme: none
Snippets enabled: 0
Restricted mode: off
Plugins installed: 0
Plugins enabled: 0
RECOMMENDATIONS:
none
Additional information
this seems to be somewhat related but iām not sure
hereās additional information. putting an alt text and width number i.e. [caption|200](web/url/image.jpg) renders the image width properly both in editing and reading view. the bug seems to affect reading view when u only declare the width number i.e. [200](web/url/image.jpg)

