No crop photo in a tall 3:4 frame
A tall frame is 3:4, a little narrower than the Portrait frame. This page opens on 1080 x 1440 pixels.
Your photo never leaves this device. To check, open your browser's developer tools, choose Network, and export a photo: no request carries it.
Tall is a 3:4 frame, 1080 x 1440 pixels. Cameras held upright often take photos in this shape, so many portrait photos fill it with little or no padding.
Landscape photos are where this frame earns its keep. A 4000 x 3000 photo fits across the 1080 pixel width and ends up 810 pixels high, which leaves 315 pixels of fill above and 315 below. Set Fill to Blur and those bands carry the photo's own colours, or choose Black or White for a gallery look.
A photo with fewer pixels than its fitted size is scaled up, and a notice gives the original and fitted sizes so you know it may look soft. A larger photo is scaled down with a filter that keeps edges clean.
Use the Size slider to shrink the photo inside the frame, then move it with the sliders or the alignment buttons. Reset puts it back at full size in the centre. Export gives a JPEG or PNG of exactly 1080 x 1440 pixels, made in your browser.