That is tough. Garland is a really bad defender for a guard. All his defensive metrics are atrocious. He's 76th out of 90 players at PG, in DRPM. And PG is a position where the defensive median is the lowest of any position. If you ranked him as a SG, he's 100th out of 116 players.
Garland profiles as a worse defender than Clarkson, which is a tough look. Physically, he just has too many limitations to ever be a good defender IMO. Just lacks both the frame and athleticism. Conversely asking for his offense to attain a level that overcomes his defensive liabilities seems like a huge ask to me. He roughly needs to be a 4-5 ORPM player.....ala someone like a Trae Young to have long term value at the position. He's currently (-0.11). 2-3 would land him in Clarkson's band.