最

Top indexing radical 曰 - visually identical to 日 (sun) in modern fonts but a separate Kangxi radical (a mouth with a tongue/breath stroke). Here it is purely an indexing assignment; the original top of 最 was a helmet/cover graphic that the script regularised into this 曰-shape over time.

Bottom 取 - to seize, originally an ear (耳) being taken by a hand (又), referencing the ancient practice of cutting off enemy ears as battlefield trophies. Combined with the helmet-cover above, the original sense of 最 was 'most prized capture' - the best, the topmost, the superlative. Modern usage is purely the superlative marker (most, -est).