In many offices, normal days are closer to polished business casual than full suits. Think chinos or wool trousers, button-downs or polos depending on the office, a few knit layers, and clean leather shoes or other office-appropriate footwear.
Client context overrides office context. If you are unsure, start slightly more formal and adjust once you see the team. The same conservative baseline in this consulting dress-code guide is a sensible place to start.
You do not need a huge wardrobe immediately. Buy enough neutral pieces to create multiple combinations, then fill gaps after your first few weeks when you understand the actual office norm.