Some games evolve from their original genre into something totally different, like Fallout being a isometric tactical RPG and moving into a tactical FPS or Metal Gear Solid being a "Tactical Espionage Action" game and turning into a card battle game on a handheld device (remember "Acid!"). Dynasty Warriors was once a fighting game before it turned into an operatic hack-and-slash.
Sometimes these changes work, like Super Mario RPG being listed as one of the greatest video games of all time. Sometimes they are not well received, like XCOM's spinoff, The Bureau: XCOM Declassified.
Final Fantasy Tactics is considered one of the best games in the franchise and sold twice as many copies in 1997 as Final Fantasy 14 did in 2010. Sometimes games need a changeover to a new genre, either in the main franchise or as a spin-off to keep fresh. Even Call of Duty and Battlefield have evolved in some ways, besides moving away from World War II settings.
Some genre shifts in a franchise go over poorly, but some go on to make millions for their publishers. Some are simply great ideas - like Overwatch 2 being a story-based PvE experience.
And there are lots of games that could really benefit from genre shifts more than Command & Conquer actually being produced as an RTS, again.
Honourable mention to Jagged Alliance being produced as almost anything other than what it has been, as we've previously mentioned here.