I think any reputable bodyshop will offer an estimate on the understanding that it may change when they strip down and get a better idea of the damage; or they may not have included the real cost of OEM parts - which in my recent case made up about two-thirds of the total cost. You may find they can make small savings by 'fixing' slightly damaged parts instead of replacing with new, but if it is 'an insurance job' they probably charge full cost.

Ask them for their reasons.

.. it’s like if they are pushing for a write off.

Who is pushing - the garage? If the assessment is borderline, it is still your decision whether to write off the car for full refund, or have it repaired, when the insurer will pay less than for salvage. Who gains by writing off?