about ultra wide 3440x1440 monitor

Your very capable MacBook Pro 2019 model can connect to multiple displays as large as a '5K' display, under certain conditions. That resolution you mention is just a '4K' wide display with fewer than maximum number of scan lines.

The answer to whether you can get the full resolution depends on exactly what model display you are connecting. It is also limited by limitations of certain interfaces -- some are more capable that others.

What make & model display are you connecting, and how are you connecting? please mention EVERY cable, dock, adapter.

Hello BoxfordStar,

You can view the available resolutions for that external monitor with these steps:

1. On your Mac, choose Apple menu > System Settings, then click Displays in the sidebar. (You may need to scroll down.)

2. Select your display on the right, click the pop-up menu next to Resolution, choose Scaled, then select the resolution you want to use.

Change your Mac display’s resolution

Cheers!