I have seen videos of T-55s being used as field guns.
They pull up a few km from the target zone, and fire as indirectly as they can. Russia still had a stockpile of 100mm at the beginning of the conflict, so this is a way to use up "free" T-55 and 100mm.
T-62s are used as second-line tanks. At the beginning of the Kursk incursion, 2 T-62Ms were caught on their towing vehicles and destroyed by artillery or drones. So those tanks had been rushed in to defend a previously-quiet front.
Rumours are that the T-62 was being used similarly as a defensive tank, for second or third lines that might be breached during offensives. They likely are also used in packs of vehicles assaulting settlements. Some of these assaults have involved a dozen or dozens of older vehicles.
T-54/55 D-10 gun has a range of 16km. Which is pretty decent when you compare the 122mm D-30 or 2S1 Gvozdika, a howitzer and an SPG most common on both sides of the conflict, has a range of 15km with a GP projectile, 21km+ with RAP or rocket assist projectile. 125mm tank gun has an indirect range of around 10km, if used as a towed gun, known as Sprut, or an SPG using a BMP-3 chassis, the range can go as far as 12km. But I have not seen any Spruts in combat.
Of course the 152mm outranges all, but the 100mm to 122mm category of guns, mortars, and howitzers are so much easier and faster to move around, much faster and easier to place, the shells twice as light and allow vehicles to carry twice the number of shells.
Tanks being in used as fire raid pieces enjoy being able to move quickly after firing, whch helps with survivability and quick response to changes in the battlefield.
I also think the popularity and population of the BMP-3 and BMD-4M with their 100mm guns, have also turned these vehicles into self propelled gun pieces, capable of conducting 'fire raids', where they would move up stealthily, she'll the fortification and strongholds, then fade back. Self propelled mortars are also being used with fire raids.
An example of a 'fire raids'. Tanks that are damaged can be retrieved later and sent back to the repair depots.
Russian counteroffensive in Kursk took 48 sq.km and recaptured two villages.
FABs doing their work, including shutting down a Ukrainian crossing.
Iskanders hit a Ukrainian force concentration in the Sumy or Kursk region.
Molinya FPV strikes at a Ukrainian firing point in a house.
Abrams tank gets knocked out in the Kursk region.
BMP-3 hitting Ukrainian firing positions.
Russians stormed and captured Zelenovka. Novy Komar has also been reported to have fallen to the Russians.
The Russian flag is raised in Uspenovka.
Vandal FPV attacks an M113 in the South Donetsk direction.
Ukrainian tank taken out by the 16th SPN.