In another timeline I have India acquiring the following 4 ships;
Virat
Vikrant
Mina's Gerais
Veinticinco de Mayo
In the early 90s. They are updated and each has 2 Goalkeeper for AA defenses. The aircraft complement would be;
3 Sea King AEW
9 Sea King ASW
9 Sea Harriers (Virat has 18)
Estimated life 15 years. Would this be viable?
First obvious issue is the age of most of the ships. Now, that isn't utterly insurmountable but it does raise serious difficulties.
Second issue is the airgroup. The Indians ordered a grand total of 30 Sea Harriers IOTL (and by 2009 were down to 12 usable aircraft), your sea-going airgroup is 36... by the time you add attrition replacements, extra trainers and enough single seat airframes to have the extra squadrons to rotate through active deployment you're likely talking about needing something like 50-60 airframes.
Third issue is what's the actual purpose of getting the extra ships? Improving coverage of ASW operations (consistent with the reduced number of Harriers per ship, fewer Harriers means less ability for a given carrier to engage in offensive operations)... but I'm not aware of India having a serious submarine threat in the early 1990s, Pakistan operated a total of three SSKs...
Fourth issue... Crew numbers. You've got 2,200 odd aboard Virrat and 1000ish aboard Vikrant(but going out of service relatively soon) IOTL but you've gotta find another 2000ish to man the other two CVLs. Probably not impossible but not all that easy.
Would suggest instead if you want India to operate four carriers new construction based on either
Chakri Naruebet, Príncipe de Asturias or Giuseppe Garibaldi would be the best bet.