Apart of course for Stablecoins (e.g. Tether) where they can print as much as they want, whenever they want. And as long as the exchanges go along with it, their value per coin stays the same.

The biggest of all of these (tether) has a daily transaction volume often higher than BTC itself, has never had an outside audit, has admitted to not being 1:1 backed and is currently under investigation by the NYAG.

They've also expanded supply by ~$12 billion this year.