"We are making a study right now," Makinen said. "But it is in the plan [to build an R5].
"We expect there to be another [road] car coming soon with a new engine and that's what we need.
"But we have to wait until the homologation and production number of that [engine] is available.
"It will be an interesting project and a good way to see more Toyotas competing around the world.
"We hear from the FIA that this category is not going to change, which is good news because this class [R5] is a good one."
Makinen confirmed the design and development work would be carried out by his group at its Finnish premises in Puppolla and in Tallinn, Estonia.
"We will take a lot of the knowledge from the World Rally Car and use that," he said.
"The design work is planned here and with TMC [Toyota Motor Corporation] and TMG [Toyota Motorsports]."
Sources have suggested the Yaris model will be available in R5-spec in 2021.
Skoda's Fabia R5 has won the WRC2 championship every year since its introduction in 2016.
M-Sport's Ford Fiesta has also proved popular and successful, while Citroen offers a C3 R5, Hyundai an i20 R5 and Volkswagen has recently introduced a Golf GTI R5.
The championship has been divided this year, with a 'Pro' class introduced for works R5 entries and WRC2 remaining for privateers only.
WRC2 Pro is currently led by Polish driver Lukasz Pieniazek in an M-Sport Fiesta, while Polo R5 driver Ole Christian Veiby leads WRC2.
Camilli hopeful of WRC return
Eric Camilli is hoping the speed he showed on last month's Tour of Corsica will be enough for him to find a way back into a full-time WRC drive.
The Frenchman posted 10 fastest times on 11 stages in Corsica and was running ninth overall in his BMA-run Volkswagen Polo GTI R5 until his car caught fire 12 miles from the end of the Castagniccia test on Saturday evening.
"Volkswagen is working [to] find out what happened with the car," Camilli told Autosport.
"There were no warning lights or anything. I started to smell some fuel from the rear of the car, so I slowed to take a look in the mirror.
"As soon as I came out of stage mode, the fire came. We took seven or eight extinguishers, but it was not possible to stop it.
"Obviously, it's disappointing not get the result, but the speed was there.
"Now I'm talking to more teams to try to get back out.
"I want to get the seat back, I'm determined to be back in WRC or WRC2."
Camilli is contracted to Volkswagen, but the Hannover-based squad has consistently stated it will not run a factory programme in WRC and Camilli said he is free to compete elsewhere.
Camilli was promoted from a privateer Fiesta R5 into a works M-Sport WRC seat for 2016, before being dropped to the team's works R5 programme for '17 and '18.