On the multiplayer beta, resizing windows smaller than 1280x720 seems to completely glitch out. On a 1920x1080 monitor like mine, this means the
windows won’t fit on the screen without overlapping. A workaround is to
use a fake higher resolution scaled down. Most applications may look
slightly blurry, but Stardew Valley looks sharp once you have set zoom in-game correctly

On AMD GPUs

• AMD settings -> Display -> check Virtual Super Resolution and GPU scaling. Then set the resolution to something like 2560x1440 in Windows display settings
  

• Right click desktop -> NVIDIA Control Panel
• Open Display -> Change Resolution -> click Customize -> click Create custom resolution
• To set resolution to X by Y, set Horizontal Pixels to X and Vertical lines to Y (I would recommend either 2560 by 1440 or 3840 by 2160)
• Click Test -> Yes to changes -> Ok
• In the list of resolutions, select your new custom resolution, click Apply -> Yes to changes
• Done. If you want to quickly switch between resolutions now, you can go to Windows settings -> Display -> Resolution
  

• Right-click desktop -> Graphics Properties -> Display
• Open Custom Resolutions -> Add
• Set Width to new width in pixels and Height to new height in pixels. (I would recommend either 2560 by 1440 or 3840 by 2160). Set Refresh Rate to 60
• Open General Settings and select your new custom resolution in the Resolution menu
• If you get an error 'This resolution exceeds the maximum bandwidth capacity', try updating your display drivers. If this does not fix it, try
  plugging in your laptop/computer into a secondary monitor, then use the
  AMD/NVIDIA instructions depending on which discrete GPU you have