The likelihood is that the Scottish National Party (SNP) will secure a majority of the seats in the parliament which will then press harder with demands for another Scottish independence referendum.
There is nothing in law to require the UK government to agree to such a referendum but, politically, such demands are likely to be difficult for the UK government to sweep aside or ignore.
Scottish Parliamentaryelections are conducted using a mixture of first past the post (FPTP) and the Additional Member System (AMS) - explained at Scottish Parliament. 73 constituency members are elected using FPTP and 56 additional members are elected on a regional basis using AMS. There are 8 regions each with 7 additional members. At present, the SNP hold 61 of the 129 seats with 67 seats held by other parties. (One MSP is chosen to be the Presiding Officer).
Interestingly, a new Scottish political party, to be known as ALBA (Gaelic for Scotland), has been formed by former First Minister Alex Salmond - The Herald 26 March 2021. The party is pro-independence and plans to field candidates for some of the additional member (regional) seats.
Scottish voters rejected independence in the 2014 referendum. The vote was 55.3% against independence and 44.7% in favour. Given SNP dominance in Scottish politics in recent years, it is doubtful whether that referendum could have permanently settled the independence question. In any event, the situation changed due to the 2016 EU Referendum which led to Brexit even though Brexit was unwanted by a majority of the Scottish voters. This has bolstered demands for a further independence referendum.
In the EU referendum, Scotland voted Remain 62% and Leave 38%. In terms of actual votes that was 1,661,191 to 1,018,322. The electoral turnout was 67.2%. The overall UK vote was 51.9% to 48.1% in favour of leaving the EU.
The European Union (Referendum) Act 2015 did not mandate that a leave vote had to be pursued. In that sense, the referendum was "advisory" - see previous post 16 May 2017. Politically, it was never in doubt that the referendum outcome would be followed through. The litigation in the Miller 1 case was about HOW it could be followed through and not about whether it could be.
The Scottish Parliamentary elections may result in a refreshed SNP mandate to pursue an independence referendum and an independent Scotland would seek to join the EU. The stakes for the future of the UK as a UNION are therefore high.
Wales and Northern Ireland:
The Times 29 March - Tories fear Welsh independence push if Labour loses power in May's elections
The Republic of Ireland continues to be in the EU but Northern Ireland , along with the rest of the UK, left the EU even though a majority in Northern Ireland voted remain in the 2016 EU referendum. Under the UK-EU withdrawal agreement, the Northern Ireland Protocol applies. These arrangements do not appear to be stable with the result that the future direction for Northern Ireland is also unclear.
Note ~ Mr Salmond and Mrs Sturgeon:
In March 2020 Mr Salmond was acquitted on all charges of sexual assault, a decision that prompted his allies to suggest he had been the victim of a witch-hunt within the Scottish National party. - The Guardian 23 March 2020.
In March 2021 a Scottish Parliamentary Committee found that Nicola Sturgeon misled Parliament over her handling of sexual harassment claims against predecessor Alex Salmond- Politico 23 March 2021.
Also in March 2021, Nicola Sturgeon was found by James Hamilton, a former Director of Public Prosecutions in Ireland, not to have breached the Ministerial Code in her handling of sexual assault claims against Alex Salmond - Politico 22 March 2021 - see the report.