Control mobile data speed

Here in Finland mobile data connections are getting extreme fast and that also means higher exposure to cell phone microwaves. 95% of new phones are 5G implemented.
There are extensions to read mobile data speed and show it but I haven’t found any one controlling mobile data speed.
Do any one know how to do it? BW Ruler seems not not work anymore with newer Androids (aka Lineage 18.0 = Android 11).

So basically I can come up with few ideas how to decrease mobile data transfer (in/out):

  1. Somehow make an extension, which switches 5G->4G->3G->2G and works this way to decrease mobile data by the lower frequency/higher latency etc depending on local telecom provider network speed.

  2. Mobile data ON/OFF switch. This Switch could operate in milliseconds and perhaps allow connection still working on while throttled by the phone.–>Perhaps cutting mobile data speed to half, quarter, 1/8, etc?
    (will need background operation implementation).

  3. Some other genius way to control packets left/received by the phone?

My phone is rooted, so there are no limitations with some permissions and less file access restrictions.
So, please share your thoughts and let me know, if any developer is able to do this? Many thanks!