Hi, Can I give access to the sandbox account only?

yep. Just create the employee record in the sandbox account and assign access

@Nathan L Thank you

If it's something you're going to be doing often, I recommend creating the employee record (without access) and any necessary roles in production so they carry over with a refresh. E.g. we have some developers that should always have access to sandbox so there's a developer role and their employee records in production. That way I don't have to re-create them every time we do a refresh. I just go into sandbox, add the role to their employee record, tick the give access checkbox, and they're all set.

@James Morris Thanks! I appreciate you! We are going to have some work done by consultants and eventually they will get access to the PROD but for now we just want to give them access to the SB. I did create their records in the PROD account but I do not want to refresh the SB yet...