You might consider getting a smart tv. We recently upgraded our tv so we could get 4k streaming. (It is amazing how much difference this makes for older eyes. We also sprung for an OLED model, in which each pixel is its own light source. Compared to our 15 year old HD tv, the brightness, color control, and precise definition make a HUGE difference for me, with an assortment of older eye issues.) Most modern tv’s are “smart” tv’s; the search function will generally tell you where you can watch.
Even if you don’t have a smart tv, you can spend $30 and get a Roku box that will attach to the cable on your existing tv. The Roku search engine will give you options.
If I’m still having difficulty, I will also go to Letterboxd, which has many useful apps including a “where to watch” box on the left side of the screen, right under the picture of the cover/poster art for the movie on which you have searched. Letterboxd is also great for logging the films that you watch (and rating them, if you want), and for maintaining a watchlist of films you want to see. Just go to Letterboxd.com and set up a free account.
Beyond that, I’ve bought or rented movies from Amazon, Google, YouTube, and Bleeker Street. For a movie that I want to own, I’d rather buy directly from the distributor if I have that option. I’m into cutting out the middleman as much as possible.
There are probably many other options. If all else fails, just google on “where can I watch RRR” and see what turns up.
Hunting can be part of the fun. A couple of films that I was having trouble finding, I eventually found on Kanopy, which was established as a resource for schools, universities and libraries. Many U.S. libraries have subscriptions. Here in DC, I can watch up to six movies a month free via my library card; I just set up a membership, saved my card number into it, and I’m good to go. Kanopy is especially good for older and foreign films. Whether it has many new releases, I don’t know.
We upgraded our older 1080p high-def box TV to 4k 55" flat screen a couple years back (LG OLED). There is no comparison. The resolution is like looking through a window. Plus, they upscale everything, even old shows of the time broadcast in 480 resolution (4:3 aspect ratio).
As for 8k, I see no need for it unless projecting on a large screen or a huge display in your own dedicated large theater. 4k is great for the 55" to 70" display depending on your seating distance.
I've been promoting 4k for some time on this forum. The prices are dropping dramatically for those who thought they couldn't afford them. Why bother with the inconvenience, noise, hassle, crazy snack prices at theaters when you can have a better experience at home. With a decent inexpensive receiver and surround speakers, you have your own movie experience.