As at 29/09/2020 it has to be enabled in Canary using a flag - chrome://flags/#enable-holding-space
See this ChromeUnboxed article dated 17/09/2020 for more details.
30/11/2020 - Checked above article again and the published date has not changed
16/11/2020 - tried looking for flag in Cloudready on Tower - not there yet.
23/11/2020 - tried looking for flag in Windows 10 on Tower - not there yet.