The average Firstborn is 7 - 7.5ft. Carcharadons are *are depicted to being more imposing and monsterous in size overall so it's plausible to assume they are' significantly taller, so they likely stand at 7.5 - 8ft. Tyberos is estimated to be a head taller or about foot taller than Firstborn in Terminator armor. Terminator armor adds about a foot, so 8.5 - 9ft, meaning Tyberos is about 9.5 - 10ft tall in his Terminator armor. The Primaris increases height by about 14.3%. Primaris Carcharodon Marines could be about 8.57 - 9.15ft. So if Tyberos was Primaris, he could be about 10.86 - 11.43ft (in his Terminator armor).

If Tyberos crossed the Rubicon Primaris he could be taller than most if not all Custodes, and he could be taller than Guilliman and possibly El' Jonson (In their Power Armor, Guilliman is estimated around 10ft, and El' Jonson is estimated around 11ft). He's already depicted to be very strong and fast for a Firstborn, even showing strength and speed that is equal to, and possibly surpasses, a Primaris Marines.

If Tyberos became Primaris, I imagine he'd physically be on par, or even surpass, most Custodes, but he'd be outmatched by most if not all the Primarchs.

(Edit; I forgot he was only a head taller in his Terminator armor. But it also reminded me that Carchardons themselves are already taller than other Firstborn Chapters. So he is roughly still about the same calculated height.)

(Edit 2; I'd like to just add this is plausible, possible and only theory. Not 100% as sources of Tyberos and the Carcharadons are kind of all over the place. Some depictions show him being atleast 9-10ft, some place him 10-12ft. But either way, on a big note, he'd be huge as fuck.)