I would do it. FYI, I have owned Sony A6500, A7RII, A7RIII, A7III, A9 and currently own Sony A7RIV, A1, A7SIII.
The 61 megapixels of the A7RV (same as the A7RIV) is really a big and noticeable difference from the 42 megapixel sensor of your A7RIII.
(Quote from Cameradecision.com article); " Sony A7R V's sensor provides 19MP more than Sony A7R III's sensor, which gives a significant advantage in real life."
And the A7RV has the latest AI processor for the best in AF performance, tracking and subject recognition, and dozens of other improvements over your A7RIII, including latest touch menu, 9.44 million dot EVF , and a five-way articulating LCD screen with 63% higher resolution than in the A7RIII.
A comparison of both models here:
https://cameradecision.com/compare/Sony-Alpha-A7R-V-vs-Sony-Alpha-A7R-IIISony E-mount is the World's largest produced and used mirrorless lens mount with over 200 quality native E-mount lenses from Sony , Sigma, Tamron, Samyang/Rokinon, Viltrox, Tokina, Laowa, Meike, and more. And new E-mount lenses are being released constantly in all budget ranges. NO other mirrorless lens mount and selection of mirrorless-designed lenses comes close, none. Mirrorless-designed native E-mount lenses will always work better than any adapted lenses on Sony bodies.
https://en.wikipedia.org/wiki/List_of_Sony_E-mount_lenseshttps://en.wikipedia.org/wiki/List_of_third-party_Sony_E-mount_lensesFYI, I was a pro Nikon and Canon user (both brands) for over 40 years and moved over to Sony mirrorless and have no regrets. Sony still has the most complete fullframe mirrorless system IMHO. Sony still leads the world in image sensor development and production, and BTW those Nikon mirrorless cameras all have Sony-built image sensors.
Five of the World's Top News Services have gone exclusively to Sony mirrorless for all their staff photographers and staff videographers Worldwide. Associated Press, UK's Largest News Service, Canadian Press, all Gannett media including USA Today have all gone to Sony exclusively for their staffers worldwide. AFP (Agence France Presse) helped test and develop the Nikon Z9 and uses the Z9 for its staffers.
https://alphauniverse.com/stories/why-the-associated-press-just-switched-to-sony/https://petapixel.com/2021/11/17/sony-is-now-the-exclusive-camera-provider-for-gannett-and-usa-today/https://www.dpreview.com/news/4545693607/the-uk-largest-news-agency-partners-with-sonyhttps://petapixel.com/2022/01/31/canadas-largest-news-organization-moves-exclusively-to-sony-cameras/#:~:text=Canada's%20Largest%20News%20Agency%20Moves%20Exclusively%20to%20Sony%20Cameras,-Jan%2031%2C%202022&text=The%20Canadian%20Press%2C%20the%20largest,provider%20for%20the%20media%20company.
https://petapixel.com/2022/06/09/how-pro-photographers-helped-make-the-z9-from-prototype-to-flagship/Cheers and best to you.