This is hard to just "tolerate & bear".
The simple things that should be there (like Smart view and Link to Windows) are just not there in that phone. Samsung Members have correctly said that this Galaxy A12 has hardware limitations, inasmuch that it's an entry-level budget phone. What's required to perform the mirroring is Chromecast. Just simply a Google Chromecast dongle set up by the Google Home application can give an experience of mirroring.
Just download Google Home on Play store and get a simple Chromecast...
Plug the Chromecast to a display, TV or projector with a power supply,
Detect the Chromecast with the Google Home application,
Follow the steps to connect it to WiFi,
Wait for it... then you're done! ✔️ Finally you can easily mirror and cast videos/music to a display without lag.
Additional settings are:
Get Quick Settings on Play Store,
Open it, click on Multimedia,
Tap on the Cast-icon tile to enable it (beware of adverts)
Scroll down from the top of the screen
Edit the buttons to get the Cast-icon,
Drag it to the panel,
Then you are all set.
