I don't think it comes as a surprise that Canon will be releasing firmware updates for the Canon EOS R5. I have been told that we will see an update “soon”, no date was given. As with most firmware updates, it'll be released when it's done.
The source claims the following will be added to the Canon EOS R5, but cautions it may not come all at once in a single firmware update.
- Addition of Cinema RAW light option to 8K recording
- Addition of CLog 3
- Increased record time limits (but don't expect a huge boost)
- Various bug fixes
These additions may not be all that is coming, but the source claims these features are what's coming first.