Three of my bikes have a matte paint finish and being a keen car detailer, this is something that I looked into a while back.
I wash all of my bikes using Muc-Off Nano-Tech Bike Cleaner (using a large soft bike brush), rinse and wipe dry with a microfibre cloth. Once completely dry in the sun, I treat the matte frames with Muc-Off Matt Finish Detailer. This works really well, doesn't impart a horrible shine onto the paintwork, and is really easy to apply (wipe on, wipe off).
For the gloss paint finishes, I use Chemical Guys Hybrid V7 sealant and detailer for outstanding results.
The drivetrain and chain are treated with specific products.
All of the plastic, rubber and leather parts of the bike are treated with a product called CarPro PERL.