I want to say welcome to people when they enter my private office. I am not in a store or selling anything. I have only heard this term used in large common public areas. There may be a more appropriate term. Thank you.
No, いらっしゃいませ is rarely heard if you're not in a store or a restaurant.
Instead, you can use:
- ようこそ。
- ようこそいらっしゃいました。 (politer)
- いらっしゃい。 (i.e., without ませ; casual and relatively uncommon)