If you are awesome at picking this stuff out, then maybe do it yourself. I flip a lot of houses and am horrible at picking colors (literally have no God-given abilities). So I hire a designer that charges $190 for a 90-minute consultation. For a light rehab, I can get everything picked out in 90-minutes and out type of fence material and style, deck shape, wood type and style, cabinets, interior and exterior paint colors, curb appeal, hardwood stain color, front door style, etc.
For a more extensive one, I schedule a 2nd consultation at Lowes and pick out carpet style and color, what type of laminate planks to use, tile backsplash styles, colors and patterns for kitchen and bathroom, door styles, trim styles, faucet fixtures, shower glass door, toilet style, fireplace brick paint choices, etc.
One thing to be careful with a designer is that they will tend to take you way over budget. So I scope my project in detail and let my designer know thing I have a budget of $3 per square foot for the flooring here or I can go $40/sq ft for countertops here. With a detail scope with exact measurements and budget, I can find the best options for my budget. Most times, I make my budget so conservative that actual costs tend me be 50% to 60% lower than my estimates. I would rather over-estimate than underestimate.
I also hire a lighting specialists on all of my flips and get all the lighting fixtures picked out in 90-minutes, but don't necessary do this on our "fix and refinance" to rent properties.