Are there toe clips/straps that are oversized to comfortably fit a men's 14/15 shoe?
There are plenty of strapless clips on Wiggle which come in extra-large. An example is this https://www.wiggle.co.uk/mks-steel-toe-clips/
Top Features: 3 sizes Medium Euro 36-40 Large Euro 40-44 X-Large Euro 44-48
44-48 Euro is size 12-15 US, 11-14.5 UK