Reducing size of large header image

I found the perfect theme I would like for my site, however, the only downside is, the header photo is way too large (with tractor image). I would like to have 9 (3×3) or 8 (4×2) rows of small icons above my 9 my services blurbs just as your site displays. Reducing the size of the header image would allow the perfect amount of space.

Is this possible for me to scale back on the huge header image? I do not need any image there except possibly my logo and slogan. If so, may you please share how? I am familiar with WordPress, but your expertise would save considerable time.

Thank you
Monique T

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