My son is currently somewhere between medium and large so we usually take the large and it's often baggy for him.
These (big ones) were very tight for him. Go at least one size bigger! Otherwise they appear to be reasonably well made and are likely to be comfortable.
🦖 HLMBB Dinosaur Toddler Underwear Training | Boys' Clothing for Easy Potty Training
44 Review
Comfortable & Durable: Lucky & Me Noah 🩲 Boys Boxer Shorts 5 Pack - 100% Cotton Tagless Underwear
49 Review
Comfortable & Practical City Threads Underwear: Sensitive-Friendly Boys' Clothing
47 Review
👦 ViCherub Boys' Black Large Underwear - Pack of 3 | Boys' Clothing Collection
42 Review
Funny Guy Mugs Tearaway Sweatpants: Playful Boys' Clothing for Fun and Active Days
49 Review
Waterproof Cozy-Dry Rain/Snow Pants for 💧 Kids by JAN & JUL, with Fleece Lining
64 Review
👖 Boys' Outdoor Climbing Convertible Trousers - Waterproof | Clothing
47 Review
Boys' Adidas Active Sports Tricot Athletic Clothing
45 Review