Those temps arent troublesome btw, but:
yes increasing case airflow, by either adding more or better fans, or creating good airflow, will decrease your gpu temps, done proper you will even decrease them quite a substantial chunk
Most cases come with a vent/mount hole on the side, near the gpu area, for a reason 😉
just by adding a fan there can affect GPU temps significantly, a good rule is: the side hole is at or below the GPU, make it an intake fan, is the hole higher than the gpu, make it an exhaust
For optimal longevity you want a positive pressure case, meaning more intake than exhaust, and this will perform fine and just great in terms of cooling. (yes yes people hail that negative pressure is the supreme cooling, but positive is just great, and better for "long life" due to less dust)
what you want in a fan, high amount of air moved, usually this is marked by CFM, or m³/h, you want that value to be high, the higher the better, and makes it easier when comparing fans, even more so if noise truly isnt an issue, look at 2 fans in equal rpm range and pick the one with higher CFM/ m³/h
Some fan specs display static pressure, again higher value is good, but high static pressure vs CFM is usually only important when dealing with rads or such obstructions, and you generally want unobstructed airflow in an air cooled case
So, back= exhaust, top back if present = exhaust, front = intake, side if at or below GPU = intake, side above gpu = exhaust, bottom fan if present = intake, but its more important to focus on front and side fan intakes first
again strive for positive pressure, so more intake than exhaust,
1-2front intakes, 1 side intake and 1 back/top back exhaust and you should be great temp wise if your fans are solid quality big airflow moving fans