Offer free Internet for a period of time.

One for older properties that haven't been fully Rehabbed or who's vacants are being rehabbed during turns but still need occupied units to be rehabbed; A Renewal Rewards Program (similar to a Frequent Flyer Program): Offer a variety of upgrade item options to viable (in good standing) residents (value add items you plan to do anyway on turns) that have different values to each item. The items will vary depending on your property's needs and your preapproved Renovation items. The longer the renewal lease period and higher the increase, the more they get to choose from. Perhaps as follows depending on your pre-approved budget and Reno budget: 1) a carpet clean 2) a deco wall with choice of one of 2-4 predetermined paint colors,
3) upgrade to a new energy saving lighting package 4) brushed nickel hardware throughout 4) new counters bath and kitchen 5) an "entire" unit new paint job 6) a new appliance 7) an entire unit new carpet & pad a new appliance package with new finishes, same as upgrades you are doing in vacant turns. This way you are offering upgrades you already planned and are approved to do and you are closing the rent loss gap, while at the same time giving Renewal Rewards to your residents, and saving them from moving out during an ongoing full Renovation.

A “smart” thermostat that they can control from their phone.
An echo or echo dot
Smart bulbs to place in there fixtures

Free Rent for a year! ( we can dream can't we?)
Free rent for a year ONLY applies to those who are current on their monthly rent who never got a note or call for rent due.

Offer a carpet cleaning.

Have you looked at services such as Livly, Modern Message, Cobu?
I always loved offering to paint an accent wall, unit upgrades, etc.
You can always offer gift cards to the meal delivery services in your area, even grocery delivery.