In-game windowed (Alt+Enter, game remembers). ShiftWindow (+ border = borderless) & to position.
(PLP screenshot with bezel effect)
Optional FOV (recommended, not req'd): Two method choices.
#1. Shortcut/launcher argument +seta com_allowconsole 1, start game. Open console (`) & type: g_fov ##, close console (`).
OR #2. Add shortcut/launcher argument: +g_fov ##.
NOTES:
1. Stock FOV is 80, screenshot is 85. Achievements are perma-disabled if console is used once.
2. Mouse sometimes leaves game's window. If it's bothersome, use PrimaryLock (details in guide/parent page). Failing that, use Cursor Lock or spread window slightly further past bezels.
View guide for general help with the instructions.