Perhaps this...
In the bin, add CROP TO ASPECT RATIO 9:16 and BLUR effects; place on track one.
Track two - same 16:9 image.
Export - 1080x1920 (9:16) Letterboxed.
Anything outside of the 9:16 frame will be clipped. BG remains stationary. Insert on track two can be scaled, positioned or otherwise manipulated.
A pan-centered, slightly scaled-up result ... 