Relative brightness control like making a light brighter or dimmer is one of those basic features surprisingly missing from SmartThings: Feature Request: Relative Brightness control / Step Dimming for Lights and Groups
For just a step brighter / dimmer there are workarounds like the virtual dimmer I linked in the feature request or custom drivers for the lights if available.
Brightening while on hold until release is a different beast though. With proprietary systems like those remotes for Lutron, WiZ, Nanoleaf, etc. where everything is the same brand they can optimize things so the experience is seamless and elegant.
I would use the virtual dimmer and just change the brightness step by step for better control, even if that means pressing a button twice instead of holding and release.