There are two types of runners in Bottles:
The Wine runner is our favorite runner, it is used for all Environments and is therefore in all bottles created, but also for wineprefixes imported into Bottles. We offer 2 different builds:
chardonnay (our runner, available by default in Bottles v3)
Includes patches from wine-staging and lutris, which increases support for compatible Windows applications.
It contains several patches for specific gaming titles support, implements OpenVR support and integrates dxvk (installable on wine from the bottle preferences page).
The Proton runner can be installed from the Bottles Preferences page and choosen on bottle creation selecting the Custom Environment. You can also switch from Wine to Proton at any time by changing your bottle preferences.
You can install new runners in one click from Bottles Preferences.
If you're feeling fearless, you can enable Release Candidates to download and then test premature versions of Wine, which may include greater software compatibility at the cost of bugs and possible regressions.