No solution found.Just have to do it manually 
Topic summary
Need: Merchants upgrading to Online Store 2.0 want to retain tag-based filtering by copying product tags into metafields for use with the new filters, often at large scale (1,600–4,000+ products; tags from integrations like NetSuite).
Early workaround: Manual entry into metafields works but is time-consuming.
Current options and updates:
- Ablestar Bulk Product Editor: Bulk copies prefixed tags into metafields using placeholders; confirmed successful by a merchant. Free plan allows 5 edits every 30 days across unlimited products (e.g., 50 tag types would take ~10 months unless you upgrade). Automation via “Automatic Product Rules” can map prefixes (size_, color_) but likely requires a paid tier; cost concerns noted.
- Shopify Search & Discovery: Enable Filters > “Tags (displayed as More filters)” to surface existing tags as filters. Quick to enable but less flexible than dedicated metafields.
- BigStart CopyTag app: Copies exact/prefixed tags to metafields, can group tags; positioned for more complex cases; video demo provided.
- Shopify Flow: Template “Convert tags with a prefix to a product metafield using the Run code action” can do this without an app. Limitations: typically on product creation or manual runs; won’t auto-remove deleted tags.
Status: Multiple workable paths; no fully native, continuous two-way sync. Choice depends on automation needs, complexity, and budget. Video demos are provided in the thread.