A well mastered technique

DEX increases your AC if you’re wearing light armor. Generally though, as a rogue, you should try to stay away and avoid getting attacked at all. When you are attacked, you can use uncanny dodge at 5th level to cut the damage in half.

When wearing light armor, you can still benefit from your DEX modifier to AC by up to +5. That means that when wearing Studded Leather (the best light armor), your AC is 12 + DEX(mod). So, when you get your DEX to 20 (do so as quickly as you can), your AC will be 17, and can go higher if you find magical armor or other magic items that boost AC.

Otherwise, yes, additional sources of AC do include grabbing a shield or taking the dual wielder feat once you max out your DEX. Or you can multiclass in a class that gives better armor proficiency, but both will sacrifice your DEX bonus and stealth abilities.