Some points in this answer are duplicates of others already raised, but some are not. I am writing this answer for the general audience, as it’s likely the original poster resolved the problem by now.
Most modern bottom brackets with cartridge bearings are not meant to have their bearings serviced. It is often hard to access the bearings, as others have noted. In some cases, manufacturers explicitly design their bearings to be serviced, and may require it for warranty coverage. If you don’t see explicit instructions to do this on their website, you can assume they aren’t designed for service. The current instructions for Hope bearings don't mention service, and that was likely true of the BB model the original poster referenced.
Users should naturally avoid spraying water, especially pressurized water, right at their bearings (i.e. spray your bike from the front or back, or if from the side, avoid aiming right at the BB and the hubs). Users should also be aware that rides in the rain or rides where the bearings get submerged will affect bearing life.
Optional reading: serviceable cartridge bearings
Ceramicspeed and Kogel focus on low-friction ceramic bearings, and they do explicitly require riders to regrease their bearings. Chris King doesn’t exclusively sell ceramic bearings and has historically focused on durability rather than low friction, but they also require users to regrease their bearings. Their service instructions are here. They have one protective sleeve over the bearing, plus a removable metal clip, plus a rubber seal. They explicitly say "The seal is delicate so take care. It should come off very easily..." The photo below shows the removal process with a penknife.
I am not completely sure about this part, but my impression is that many cartridge bearing seals may not be designed to be repeatedly removed. Enduro Bearings, which supplies bicycle bearings, alludes to this on their page on seal design. They list 5 different sealing arrangements they offer. On one of them, the Enduro SRS seal, they state:
... these seals employ a snap ring that can be removed with a small knife for quick and easy servicing. These seals can be removed with no danger of bending them while performing lubrication service, ensuring they will spin as smoothly after.
This implies that many other seal types they offer are not designed for removal and replacement. My impression is that seals not designed for removal might be damaged if you remove or reinstall them. Kogel alludes to this in their instructions on bearing service, and their instructions seem to assume that the old seals should be discarded. However, one of their representatives said to me in a phone conversation that it was possible to reuse their seals if they were intact.
Additionally, seals can be designed to have more or less drag - for example, seals that have a more solid contact with the bearing races will have more drag. The tradeoff, as I understand things, is that lower-contact seals should be less resistant to contamination. If a seal is less resistant to contamination, then unless the whole bearing is designed to be an extremely high cost disposable item, it would make sense to make the bearing system serviceable. Kogel’s seals came off easily when I serviced them. I’d assume they are a light contact seal.
Last, the low-friction bearings may have less grease, and more viscous grease. My understanding is that less viscous grease has a shorter lifespan. More viscous grease should prevent more dirt from entering the interior of the cartridge than less viscous grease. I suspect that general purpose bicycle greases are on the more viscous side unless specifically identified. Chris King, Kogel, and Ceramicspeed all sell lighter and heavier greases for a range of use cases. If you use a lighter grease, I would suggest planning on more frequent service.
Back to point 2
This was where the OP asked:
Do ceramic bearings require different maintenance procedures?
As stated elsewhere in my answer, I believe that a ceramic bearing of similar construction - including seal design, grease type, and amount of grease filled in the bearing - to a steel bearing should not require materially different maintenance procedures. If the manufacturer instructions did not require periodic maintenance, there was nothing the OP could have done differently. Others in this situation might want to double-check with the manufacturer for specifics.
That said, because of their high cost and slightly lower friction, I think that ceramic bearings on bikes may generally be designed with lighter seals and grease fills than average steel bearings designed for durability. Bearings designed to optimize friction are likely to require more maintenance.
Creaking should be a sign of a loose fit, not necessarily of failure due to contamination
Speaking in general, a) creaks can sound like they’re from the bottom bracket but actually come from other parts (e.g. loose skewers are a frequent culprit), and b) creaks are usually caused by parts that fit loosely, e.g. a bottom bracket in a shell that is out of tolerance, rather than contaminated bearings. In general, I believe that contamination will cause the bearings to feel rough, and that they shouldn’t cause audible sounds unless the bearing is very bad. This is not aimed at the OP, as we were asked to assume that they had isolated the noise. It is more for the general audience.
