Hello Sam Gill1, Welcome to the Microsoft community.The feature is not yet available in the official version and is currently confirmed to be available for the Office Preview Experience program. If you are using the official version of Microsoft 365, you can open File>Account and choose to join the Preview Checkup program (we recommend that you choose Current Channel), which will be available in Insert after the update. If you don't want to update to Preview, try using CheckBox in Developer.First you need to add the Developer tab, please open Excel and select File>Options>Customize Ribbon, check Developer in Main Tabs and click OK. After selecting Developer>Insert>Check Box, you can insert Check Box in the cell.
After that you can adjust it according to your needs.
Sincerely Carlos - MSFT | Microsoft Community Support Specialisto