if you are only running twice a week i wouldn't do anything fast and time soon. By dar your biggest bang for buck training change will be to increase volume.
I wouldn't bother with a timed race more than once a month.
set some better goals like running the same pace with a lower Heart rate, or similar a faster pace for the same heart rate. That will indicate your fitness improvements. Once a month time yourself on a fixed route.
TBH, running is very different to sports like cycling and swimming. Very hard efforts don't yield big returns, and have a high risk. Also, the optimal training means your legs get quite fatigued and it can be hard to realize your potential without a good taper (2-3 weeks of gradually reducing running). But if you do that you frequently you miss out on training and will loose fitness
. So runners tend to race less than in other sports, especially sd the distance increases. e.g. 1-2 marathons a year. I go 6 months without racing just slowly building fitness, without a good idea how fast i really am until race day.
This has a big sense of achievement because your new PR is the product of 6 months hard work.
For sure as a beginner you will get new PRs quite regularly, but it is useful to get in the mindset of s long, slow gradual, patient build up
