There is no such thing even for android. All those stupid apps do it try to force it to connect to a different cell tower or AP. So you in effect turn the connection on and off and assume it will connect to the strongest signal when it reconnects. If all you care about is getting more bars on the phone then yes they work but you are not going to be able pass any data while its disconnected. It in no way increases the signal strength form a single cell tower or wireless AP
Now a phone does decrease the radio power level when it is not needed to conserve battery but almost all have a option to not run in power saver mode.
A PC normally run wireless at full power all the time. There is no way to increase it since the hardware is designed to prevent you from violating any law related to radio transmission power. You can if you want buy illegal equipment but the fines are huge if you get caught.