I think with indoor homing it really depends on the individual cat.
Obviously both my boys being FIV+ had to be indoors anyway, but they were both picked up as strays, so had been well used to outdoor access for a period of time.
Max coped, he would have liked to go outside I'm sure, but he had enough toys etc to keep him occupied.
Poot is way more settled than Maxy was, you can leave the front door open and he just has no interest in it at all, just wants to have cuddles and then his dinner! He's never made a break for freedom, whereas Max would try it every now and then if the front door was unmanned for more than a few seconds lol!!!