If u have a small deformity and your grip is weak due to RA. How can we have a strong grip and stop deformity from developing?

Two steps. 1. Have your rheumatologist check to make sure the RA is well controlled with no active inflammation and also check for any underlying structural damage. 2. Get a referral to a hand therapist for strengthening.
Joint protection. Joint protection and splints may be very helpful. See rheumatologist who has experience with deformity prevention.