At boot the display will seamlessly transit from the firmware boot-splash into the new plymouth theme, which uses the firmware boot-splash as background:
If you are using full-disk encryption then the unlock dialog will look like this:
Last, but not least the new plymouth theme looks like this in offline-updates mode:
ATM the texts in the offline-updates theme are not translated. They are rendered using pango + cairo, so we have the capability to make this fully translatable into all languages, I just need to add gettext support to plymouth for this. I plan to do this next week.
This all assumes that you are booting your machine with UEFI and your firmware supports the BGRT extension (which almost all firmware does). Otherwise you will get a dark-grey background instead of the firmware boot-splash.
If you are running rawhide and are seeing a totally different boot-theme then you likely have changed your plymouth theme away from the "charge" default at one point in time; and in that case you are not automatically updated to the new plymouth theme. To switch to the new theme run:
sudo plymouth-set-default-theme -R bgrt
If you do not like the firmware-splash being used as background, you can use the new theme on a dark-grey background instead by running:
sudo plymouth-set-default-theme -R spinner