Please don't talk about a power amplifier without looking in Google for its datasheet.
The LM386 is a small, low power amplifier for toys. With a 6V supply, its output into an 8 ohm speaker at clipping is only 200mW. With a 9V supply its output is 450mw. With a 12V supply it might melt while its output is 530mw. That is 1/2 Watt! About like a little clock radio.
Pins 1 and 8 on an LM386 are for gain control as shown on its datasheet.
An amplifier for 7W into 8 ohms will need a power supply voltage of about 25VDC. It will get hot and will dissipate about 6W so it would need a pretty big heatsink and a big power supply.
Gain is just sensitivity, not power. If you are listening to someone talking on a radio then they suddenly whispered, you turn up the gain to hear them at the same power as when they were talking.