I will apply some Lightroom adjustments before taking the file into the plug-in.
There are packages from the likes of Adobe, Affinity, Capture One, DxO, Luminar and Topaz. Some are available on subscription, others are outright purchases and there are free/shareware options too. Most of my mono conversions are done through Silver Efex from DxO’s Nik Collection which I use as a plug-in in Adobe Lightroom. I will apply some Lightroom adjustments before taking the file into the plug-in. Usually, it’s some highlight and shadow control, plus tweaks in contrast and clarity.