Roshan Shankar,
Many Pixel 3 and 3 XL phones do not have eSIM capability. In fact, only US model 3 and 3 XL phones purchased from Sprint or Google Fi have eSIM. 3a phones purchased in Japan and/or models bought with Verizon service do not have eSIM. See the Google Support article at the below link:
Unfortunately, there is often user confusion about what constitutes an "unlocked" phone. When retailers refer to a phone or phones they offer for sale as "unlocked," they are almost always referring to phones that are carrier unlocked and can be used on any compatible carrier. However, those same "unlocked" phones may very well have bootloaders that are encrypted and cannot be unlocked. Those phones may be used on any compatible carrier, but their bootloaders will remain locked. All phones purchased from and/or associated with Verizon, even if carrier unlocked, will still have encrypted bootloaders that cannot be unlocked. This may be true of phones sold by some other carriers as well.
In the end, it doesn't matter if your phone's bootloader is associated with a carrier other than Verizon, what matters is that it cannot be undone.
Lilybell2