Editor in create event section is expandable in one direction only.

[yashasingh]

You could increase the editor since there is lots void space left.

[kunalvishnoi]

In bar of text editor , full screen view option is already present !!

[yashasingh]

@kunalvishnoi True that full screen option is available on the editor, but it is not often that user wishes to go full screen. Issue is that currently, editor provides flexibility to resize itself as user wants, but is actually it is flexible only vertically, not horizontally.
Moreover size of the present editor seems quite small. Observe these sizes-