This has been on Android for some time now and I believe is being rolled out to IOS soon.
You can get the majority of the new layout and features by enabling the ‘connect your Barclaycard’ option in labs but some are still missing. Eg. Pot history.
You can also read up on the discussion surrounding this new layout here:
https://community.monzo.com/t/a-new-look-for-the-account-tab/57705