need more I/O pins than MEGA, What to do ?

i am making a project where i need more pins that mega already have
for example only 3.2 inch lcd is gonna take 28 something pins and then i am only gonna left out with few so what to do then if i need more ?

can i use another arduino uno and connect it to arduino mega via SERIAL and make them talk to each other ?

help would be appreciated

Offload some of that stuff to helper chips.

Port expanders, shift registers, multiplexers, display drivers, something.

You can also use the analog pins as GPIO pins if you are not using them for something already. That gets you another 16 pins for a total of 70.

Do you have to use that particular LCD? There are plenty that you can talk to using serial communication.

Or, as you suggest, you can talk to another Arduino and have it handle the display.

As noted above, there are many ways to get additional pins.

You could use shift registers if you just need outputs or inputs (most shift registers, particularly the ones we talk about here, are for outputs, but there exist ones that act as inputs too). If you need more advanced functionality, you can use a port expander (like MCP23017)

There also exist LCD screens that are driven via SPI instead of parallel (hell, Digole sells ones with a UART interface - these have an onboard microcontroller that drives the display). These are slower to refresh, but use far fewer pins.