The RCL ships I have been on have US style outlets as well as European. I bring European to USA adapters so can use both. Just do not use one of these adapters for a hair dryer, curling iron, or fan as the higher voltage will fry them. OK to use for a computer, cell phone charger, etc. as these are designed to work at either voltage. This is one set I saw online: https://www.amazon.com/Ceptics-European-Adapter-Adaptor-Charger/dp/B01NCZJ5UN/ref=sr_1_3?crid=1TPUS0LY8FXV7&keywords=power+adapter+european+to+use&qid=1583256758&s=electronics&sprefix=power+adapter+european%2Celectronics%2C176&sr=1-3. A secondary benefit is their small size for packing.

I suggest this. Turn the European outlet into two american plugs

https://smile.amazon.com/Ceptics-European-Adapter-Adaptor-Charger/dp/B01NCZJ5UN/ref=sr_1_1?keywords=europe+plug+adapter&qid=1583256525&s=electronics&sr=1-1

If you want to keep it as light as possible, then buy just the outlet plug for your existing USB charger. But these two links below are for Indonesia and (most) European countries. It will not work with Malaysia.

https://www.amazon.com/Ceptics-Europe-Asia-Plug-Adapter/dp/B0084OPT8C/ref=sr_1_4?ie=UTF8&qid=1532657803&sr=8-4&keywords=europe+plug+adapter

https://www.amazon.com/Ceptics-CT-9C-Europe-Travel-Adapter/dp/B01NCZJ5UN/ref=sr_1_1_sspa?ie=UTF8&qid=1532657803&sr=8-1-spons&keywords=europe+plug+adapter&psc=1

Otherwise, just filter the items from these https://www.amazon.com/s/ref=nb_sb_noss_2?url=search-alias%3Delectronics&field-keywords=travel+adapter .