Patchy beard at your age is very common and usually due to genetic pattern of hair follicles sensitivity to androgens.
Even if family members have a full beard, growth pattern can still vary individually.
This is not a disease and not harmful, but yes, it can be cosmetically frustrating.
Helpful Tips / Word of Caution:
• No “home remedy” (oil/onion etc.) has proven results
• Do not compare with others—beard density varies naturally
Next Steps
As a medical Cosmetologist, I've helped many people grow hair and beard.
You can book an online consultation with me via practo for detailed evaluation and treatment.