Manual

Pen Pressure

Pen Pressure should work normally.

Make sure to check that the brush you are using has the corresponding pressure option enabled, and also that the brush is loaded in the bay, after the preset been changed.
More on Brush Library here
More on Brush Bays here

Troubleshooting

Browser - Chromium browsers, such as: Chrome, Edge, Opera etc. officially support pen pressure. It is known that some other browsers do not support pen pressure, for example Firefox.

Windows Ink - it is possible that on your system configuration you may need to enable or disable Windows Ink. This option is usually located in your tablet driver menu.
It is typical for Chromium browsers to use Windows Ink, in order to read pen pressure from your drawing tablet. Though, it is also possible that your system is configured differently and disabling this option may yield the proper result.

Operating System (OS)
There is currently known only one limitation - it is that pen pressure may not work on older Windows systems, such as Windows 7 and earlier. The reason is that these versions of Windows have a different approach to pen pressure. Newer browser versions have dropped support for older pen pressure standards.