When I had Android on my tablet (Smasung Note 10) I would long press the chassis button to access a list of running applications; the long press does nothing with LineageOS.
How can I access the list of running applications with LineageOS?
It depends on your settings. For me it is settings -> buttons. There you can specify which button is responsible for which action.
By default, press the original MENU key. This is now the new default on LineageOS across devices that use the legacy MENU-HOME-BACK capacitive key layout.
Note that you can change this behaviour back to what it was by visiting Settings-Buttons - for MENU and HOME, both tap and long-press actions are customizable.