Interior design SEO works best for firms that serve a specific geography (one city or metro area) and have a clear design niche-residential, hospitality, commercial, kitchen/bath, staging, etc. If your business model depends on local clients finding you online, SEO is a core investment. Studios with a strong portfolio but weak Google visibility see the fastest results because the demand exists; SEO just makes you visible to it.
Design firms that rely entirely on referrals or interior design platform exposure may benefit less, but most studios today find 30-50% of qualified inquiries come from Google (industry estimate). If your phone isn't ringing from organic search, this is where that opportunity sits.
Brand-new studios and established firms both see results, though new studios need patience-established businesses tend to rank more easily, so ranking takes longer if you're under 1-2 years old.
Before spending more, review what prospects can already learn from the site, what is missing, and whether the firm's investment can be measured against qualified inquiries rather than pageviews alone. If your firm is 1-2 years old, focus first on accurate business information, useful service pages, portfolio case studies, and clean inquiry tracking.