My conda was buit in 1979. On my all my breaker are 20amp my wire is 12 but none of my outlet have the T like a 20 amp outlet do.could I change them

You could but why would you? The outlet with the "T" neutral slot is a 15/20 amp outlet. What appliance do you have that is 20 amps?

I agree with Harold. The average condo owner would have little to no need for 20 amp receptacles. Why go through the bother and expense but tell us what you have or may have in the future that would pull this amperage.

Unless you plan on using appliances greater than 15 amps in the future, there is no need to do this. What you are describing is extremely common in residential areas, or at least in mine. And besides, if you plan to use 20 amp appliances in the future, and we are talking normal circuits with 8-12 receptacles with many things plugged in, it is likely you would trip the breaker anyway.