“Remove Widget – You must remove a widget to add…”, but I have a lot of room on my lock screen in iPhone 17’s iOS v26.3.1 as shown in my https://matrix.zimage.com/_media_proxy/v1/media/download/AQZZwDwvpxSgU1jwq4GQLK5vh5HwR3ymc0rl1auCLEBW0WkUNPn2mI8869%20%20%20%20%20%20%20%20%20%20z-vVqA3c-b2inzdqfvgxHM9iGDC7tCedP-hzvAAHppbWFnZS5jb20vWXFxWExPeEZxUlpWSnhyYlpYVnR3ckxU screen shot/capture. 
What’s up?
The rounded gray rectangle you see beneath the clock is the only area designated for widgets on the lock screen. You have it completely full with two widgets. You’ll have to remove one, or replace it with a smaller option, in order to add another widget.
Oh wow. I thought I could add many big widgets. That’s disappointing! I could make the clock/time section very long. I just wanted my app widgets for the extra space.
Yeah, I don’t know the reasoning behind the restriction.
I’ve run into that issue myself in the past, and had assumed that was just because I’ve got an iPhone SE 2022. I’m guessing that this is a restriction regardless of iPhone size?