You can’t sadly. The only possible transfer of progress can happen from H2 to H3. within the same platform roughly.
You can’t for free in this case. It would be possible if you owned H2016 on Steam, but EGS → Steam is not a thing. You would have to buy the Legacy Pack for H2.
What you could do is to use the same IO Account to log into both H2016 and H2, buy Hitman 3 on EGS, and again use the same IO account here as well. If you follow the transfer progress, you will move your (nonexistent) H2 progress. But on the plus side, it should unlock both the H2016 and H2* levels in H3. That still is no free solution but at least comes with more content than you have with both first games.
* Note that due an ongoing issue redeeming H2 from Steam in H3 on Epic is not fully working until later this month.
Are you sure?
The one way I’m aware of is to get HITMAN 2016 GOTY Edition (or free version that been given away in mid-2020), or HITMAN 1 GOTY Access Pass.
The person that asks the question has no sense in redeeming Legacy Pack for HITMAN 2, because he doesn’t have HITMAN 2016 on Steam, and the redeeming process is available only there.
So for him the only way to gather the puzzle of all three games would be upgrading his Epic version of HITMAN 2016 to GOTY Edition or buying HITMAN 1 GOTY Access Pass directly for HITMAN 3.
As he owns gifted version of HITMAN 2 on Steam, theoretically he should be eligible to get H2 locations in HITMAN 3 for free when it becomes possible.
But one thing I would advise to @TheY0L0man is to install HITMAN 2 and play at least one mission from the very start to the very finish and maybe register the game to IOI Account
I looked it up again and might have confused it with the progression carry over. So far the level access through the IO account on EGS is still a bit of a black box to me. There are the Access Packs but it currently seems to be disconnected to the progression carryover, so I was wrong there.
It is probably better to wait for the next update on this matter.
If you own HITMAN 2 on Steam, you can get access to H2 levels within HITMAN 3 on Epic.
Developers are on it as you know and promise to make it happen any day now.
I suppose the mechanic of the process will be explained by them in a separate blogpost, or via updating the existing Player Guide.
And as for HITMAN 2016, seems it doesn’t matter if you own the game on Steam, you still have to own HITMAN 2016 on Epic to merge the game with HITMAN 3.
I haven’t seen them saying that Steam version of H2016 will be of some sort of important.
You get HITMAN 1 GOTY Access Pass for free if you preorder or buy HITMAN 3 within first 10 days after release. If you’re late, you’ll have to pay the full price for it.
If you redeemed a free HITMAN 2016 game on Epic which was available in June 2020, you can get HITMAN 1 GOTY Access Pass for free at any time.
So there is no third way of obtaining H2016 locations in HITMAN 3
I can’t tell you why, but it was a thing while redeeming Legacy Pack.
Maybe it’s needed so the system see that the game is registered and active, I don’t know.
Maybe you even don’t need this, but who knows what the system needs
Presumably you own a Standard Edition then.
So to merge games, you need either GOTY Edition or HITMAN 1 GOTY Access Pass