Anyone know of any funds or ETFs in an S&S ISA that are as safe as Cash ISA

This may seem like an odd question but hopefully it's a straight forward answer for someone more knowledgeable than myself. A family member is feeling nervous with the money they have in their S&S ISA (Trump effect) as they may need to move house in the next 12-18 months. Before I have them transfer some of the required money into Cash ISA's where it is safe from market fluctuations. I wondered if there was a fund or ETF that effectively was a cash savings account. No need to recommend something specific if there is a category name for this happy to research funds I just can't seem to find such a thing (probably as it's a daft thing to offer as for safety most would want to use a banking institute to get the 85k protection)

Previously I would have suggested Funds holding Government Bonds as safe bet but I wondered if there was anything safer whilst still given a return in line with cash savings rates and avoiding the hassle of transfers out of the S&S ISA.