@Awres
Rewards along with add ons whether they are gifted, promotional or purchased are associated with the account not the plan. Promotional recurring bonuses of plan data or monthly plan discounts with a month counter or "unlimited" beside it will disappear if you change rate plans. But you are safe to schedule a change plan on next renewal.
It is advisable to manually top up your with your new plan amount to avoid the possible autopay glitch that only charges your card the old plan amount causing your renewal to fail due to insufficient funds.
